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THE

SOLENOGASTRES OF THE SIBOGA-EXPEDITION

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Siboga-Expeditie

XLVII

THE SOLENOGASTRES OF THE SIBOGA-EXPEDITION

BY

H. F. NIERSTRASZ

Utrecht.

With six plates

late E. J. BEILL

PÜBLISHERS AND PRINTERS

LEYDEN Ig02

THE SOLENOGASTRES OF THE SIBOGA-EXPEDITION

BY

H. F. NIERSTRASZ,

Utrecht.

W i t h s i x p 1 a t e s.

I. INTRODUCTION.

Until recently, not a single specimen of Solenogastres from the East-Indian Archipelago
was known. It was only in the year 1898 that Thiele gave a short diagnosis of two Australian
forms : one from Torres-straits, one from the N. \\\ coast of Australia (9). In this respect the
Siboga-expedition has been more fortunate than its predecessors. The expedition brought back
110 less than 65 specimens, a description of which follows here.

All these specimens have been fixed in absolute alcohol, and preserved in 95 per cent
alcohol, a method, which I believe to be better than any other. And yet it is only of a few specimens
that the state of preservation may be called entirely satisfactory. The cause is not clifficult to fmd.
Only few forms lead a free life, and can undergo immediate fixation as soon as the contents of
dredge or trawl commence to be examined. Others however live in mud ; whenever a dredge filled
with mud came up, the mud had to be carefully examined and it often took a long time to find the
small Solenogastres ; during that time they had died and fixation only partly succeeded. The same
is the case with the numerous forms we find twisted around the branches of Gorg-onids. Owino-
to the large amount of work which a full dredge necessarily entails, the Solenogastres are only
detected when the Gorgonids are inspected. Consequently my sections are often of no value for
minute histological details. In the tollowing description I intend to lay stress upon the general
structure and to draw the attention to those characteristics, which are of importance for classification.

Before cutting I decalcified the animals in a mixture of 3 per cent nitric acid in 70 per
cent alcohol. Though this renders the investigation of certain forms of spicula impossible this
method is to be recommended. If not decalcified the sections may be found to be very seriously
injured by fragments of larger spicula. After decalcification I stained the animals in toto with

SIBOGA-EXI'EIUTIF. XI.VII. I

i475I

carmalum (after de Gr carminic acid i gram, alum 5 grams, iron-oxide amm. sulph. 0.1

gram, distilled water 200 grams) for 2 or 3 days, rinsed them in water, and replaced them in
alcohol. Transverse or longitudinal sections were made; several of the animals were very brittlc,
a circumstance seriously interfering with the cutting, often causing the sections to be broken.
This brittleness often made it advisable not to take too thin sections (12.5 — 15 ua.). The
diagrams in perspective have been obtained by careful reconstruction on millimeter-paper of all
the tracings of the sections that had been made with the aid of the camera lucida, the situation
and size of the organs being therefore quite correct. The spicula were isolated with Eau de Javelle.

II. DESCRIPTION OF THE NEW FORMS.

Proneomenia.

1. Proneomenia Weberi nov. spec. (Plate I figs. 1 — 22).

Stat. 33. Bay of Pidjot, Lombok. 22 M. In mud. 1 Specimen.

Stat. 45. 70 24' S., 118° 15'. 2 E. Java-Sea. 794 M. Upon Gorgonid. 1 Specimen.

Stat. 177. 2°24'.5S., i2o°38'.5E. Between Ceram and Misool. 1633 M. Upon Gorgonid.

1 Specimen.
Stat. 253. 5°48'.2 S., I32°I3' E. Near the Kei-islands. 304 M. Upon Gorgonid. 1 Specimen

(fragment).
Stat. 314. 70 36' S., ii7°3o'.8E. Java-Sea. 694 M. Upon Gorgonids. 6 Specimens.

Length 18 — 37 mm. Length-index 22 — 25. Body proximally bluntly cut off, distally
ending in a trunk-shaped elongation. Cloaca with 3 pairs of coeca, extending proximally. Radula
strongly developed with 12 — 18 rows of teeth. The salivary glands remain separated. Cloaca-
ducts with vesiculae seminales and receptacula seminis. 2 Strong copulation-spicula.

East-Indian Archipelago. 10 Specimens.

The length of the animal varies from 18 — 37 mm.; the diameter from 0.75 to 1.5 mm.;
the length-index therefore being 22 — 25. Two specimens are represented, 4 times enlarged, in
figs. 1 and 2.

The shape is cylindrical ; proximally it is slightly thickened and bluntly truncated. Distally
the animal also thickens somewhat and ends in a trunk-shaped prolongation, which may attain
the length of 2 mm. To a certain extent we find certain resemblances between this form and
X'inatomenia flavens and Myzomenia banyulensis (Pruvot 4, fig. 1 and 2). The colour is dark brown,
often greenish. The animal has an exquisitely glittering spicular investment, the spicula intercrossing
rectangularly. The ventral groove is distinct. The mouth-opening is visible as a vertical slit.

The spicula are straight or slightly curved hollow tubes, pointed at both ends (hg. 3 A.).

1 his form fully* corresponds to that of Proneomenia neapolitana (Thiele 8 fig. 52). The little

curved massive spicula (B) are found around the cloaca-opening in great numbers; those of

shape C occur at the proximal and distal part of the body, whilst along the ventral groove

spicula of shape D are met with : long, curved massive spicula, and amongst these also more
flat and broad ones. They occur in a great number of layers superposed upon each other, and
make with the body-wall an angle of ± 450. The cuticula is thick and with its many layers of
spicula gives the impression of being the integument of a Proneomenia-species. The state of
preservation does not permit of any close observation regarding the mode of formation of the
spicula. As to the papillae, of which great numbers are present, these are formed as in
Proneomenia neapolitana (Thiele 8 fig. 53), but they are comparatively larger than the latter.

A small dorso-terminal sense-knot is present on the prolongation of the hinder body.

The ventral grove runs from the cloaca-opening as far as a point close behind the
mouth-slit. There are three ventral folds : one larger median and two smaller lateral ones ;
near the cloaca-opening there is only one median fold in the groove, which divides more
proximally into three folds (figs. 6 en 7). Here too the ventral groove opens behind the
mouth-slit into a cavity ("Flimmerhöhle" of Wirén), which is small and divided into two halves
by a dorso-median septum. The "vordere Bauchdrüse" (Wirén) is present in the shape of
transparent, thin fibrillar glandular cells, staining pale-red with carmine; they surround the
pharynx almost entirely. Amongst these the cells of the "hintere Bauchdrüse" (Wirén) are
directly discernible as little round glandular cells, staining obviously. The latter are found,
though slightly developed, around the ventral folds all over the animal.

The cloaca is of a rather complicated structure. To elucidate this cf. figures 4 — 9,
representing schematic transverse sections, corresponding to the given lines of the reconstruction
fig. 11. The section after line AB (fig. 4) shows that the finger-shaped prolongation of the
hinder end is a fold of the dorsal body wall, open ventrally and thus enclosing a distal offset
of the cloaca. More proximally (fig. 5) it is seen that the cloaca itself is divided into four
divisions. The clorsal division a, of which the cavity in the finger-shaped appendage is a
continuation, is still visible in fig. 6; in fig. 7 it has made place for the rectum. Part b is a
paired coecum directed forwards, still visible in fig. 6 but no more visible in fig. 7. The same
is the case with c, a large sack-shaped coecum, directed forwards and dividing into two coeca.
The most considerable extension is obtained by d, which extends far forwards (fig. 8) ; this also
forms two coeca. So there are three pairs of coeca, running forwards ; in fig. 1 1 they are not
given. The cloaca is clothed with strongly ciliated cylinder-epithelium ; in the coeca d however
the epithelium is not ciliated and of unequal thickness, the wall being therefore undulated. The
case is different with the coating of b, the epithelium of which forms a great number of papillae
with multinucleated stalks ; the knob is often dilated vesicularly, as one of the cells swells and
becomes transparent. Between the papillae are found openings, in which during the animals life,
straight spicula are implanted (fig. 12). In Proneomenia Sluiteri Hubrecht probably describes such
another organ as the byssus-gland ; Heuscher recognised it in the same species ; in Proneomenia
vagans it also is found. The wall is to be regarded as a part of the integument, which has
penetrated into the interior, forming there an organ which may be subservient to copulation.

Of gills or folds of the cloaca-wall, which might perform the function of gills, nothing
is present.

Of the nervous system the only thing to be mentioned is, that it fully corresponds to

that of Proneomenia acuminata (Wirén, 6b, pag. 81). Only the sublingual commissure cannot
be pointed out with certainty, and the commissures between the ganglia posteriora superiora
and inferiora are wanting here.

For the structure of the digestive organs see reconstruction fig. 13. The mouth-cavity
is spacious, coated with cubical epithelium and opening into the exterior through an almost
perpendicularly placed mouth-slit. In the mouth-cavity we find ciliated "Mundleisten" (Wirén),
enclosinc numerous cirrhi. In fig. [3 these cirrhi are not indicated; they are found in cavity a.
They are broad folds of the mouth-epithelium, sometimes ramified at the basal portion. The
cytoplasma of the constituent cells is finely-granular and stains pale-violet with carmine ; at the
basis of these cells there are bigger or smaller granules, sometimes dilated vesicularly ; these
an- of a brisfht green colour. The whole of the epithelium of the cirrhi themselves is filled
with these green globules, colouring the cirrhi in the sections dark green. This points probably
towards a strong secretory function of the cirrhi, though nothing like a secretion can be
perceived. Around the mouth-cavity there are numerous strong ganglia, in continuity with the
cerebral ganglion through two strong nerves. A tenuous network of nerves connects these ganglia
and forms a network all around the mouth-cavity, sending numerous branches towards the cirrhi.
This points at the same time towards a strong sensory function.

The pharynx (/) here I follow the division of Simroth (7) - - invaginat.es some

way into the mouth-cavity and has a considerably folded wall, encircled by a strong circular
muscular layer ; these muscles are especially strong in the fold (ó). No special glands open
int" the pharynx.

A very strongly made radula is present. As usual the structure cannot be closely
investigated, the teeth having been seriously injured in the cutting of the sections. I therefore
isolated the radula with Eau de Javelle and put it without damage into glycerin ; so I can give
the exact structure. It consists of 12 rows of tolerably narrow conical teeth, directing their
somewhat curved points backvvards (tig. ijc). They are all of equal size except those of the
two middle rows, which are broader. The teeth stain pale-red with carmalum, but the strong
basal-membrane, upon which they are placed, does not stain at all. In fig. 17(7 and b and in
fig. 1 3 is representecl what is seen of the radula in the sections. In some specimens however
the rows of teeth reach the number of 18. This form of radula most resembles that of Proneomenia
vagans (Thiele 8, fig. 100, 101). This is the most strongly made radula which has been
observed in Solcnogastres ; fig. 13 gives the relative size. In all the other species, possessing
a polystichous radula, this is much smaller and less developed. There can hardly be any question
here of its being rudimentary. This is indeed the case with the tongue ; the radula is sustained
upon a single epithelium-layer. Fig. 17 gives the radula-sac a, in which new teeth are being
formed. The: newly formeel teeth are easily discernable as dark-coloured elevations upon the
al membrane, which is to be considered as a cuticular formation. The teeth touch each other
at the basal extremities. 1 ■ irst the radula takes its course proximally; then it bends, runs
ventrall) to turn again and to run proximally once more. At the second turning-point the
epithelium is thickened and forms pouch b built up of long slender epithelium-cells. In this pouch
no formation of teeth takes place, which could hardly be expected ; cuticula is formed here,

which does not stain, exactly like the basal-membrane of the radula. The purpose of this is
not clear. The basal-membrane, after leaving this pouch, does not become thicker, so that
increase of cuticular matter does not take place. Reparation of the basal membrane is possible,
as on its long course it may have become injured here and there. A strong circular muscular
layer surrounds the radula-sac, which is sustained by a few cartilaginous cells (fig. i6cc).

On both sides of the radula a salivary gland opens into the pharynx. The salivary glahds
are long, thick-walled tubes, running ventrally from the intestine.

The part next to the pharynx (the oesophagus, if at least this name may be used) is
very small and has a strongly folded wall. This together with the large fold in the ventral
pharyngeal wall, situated in front of the radula, renders it possible for the pharynx to be
evaginated with the radula. The wall of the oesophagus is built up of cubical epithelium with
thick cuticula.

About the intestine there is nothing noteworthy. The lateral coeca are of very regular
size. Gradually the intestine merges into the rectum, the epithelium of which is ciliated at the
dorsal wall. The transition into the cloaca, the wall of which is entirely ciliated, is gradual.

The generative glands are of normal structure. Both the genital products occur in a
mature state in one and the same specimen. They open out into the pericardium through two
ciliated ducts.

For the course of the cloaca-ducts see reconstruction fig. 1 1 ; it is to be noticed in this
figure that only the intestine, generative organs, pericardium and cloaca-ducts are given, and
of the cloaca only that part, into which the rectum opens out. The cloaca-ducts first take their
course proximally, then bend and run distally to unite into the large precloacal organ (nidamental
gland, Schalendrüse of Wirén, organe precloacal of Prlvot). The part of the cloaca-ducts
running proximally, which is not glandular, presents a peculiar structure. The portion, passing
out of the pericardium, is built up of epithelium-cells of unequal height, the inner surface being
therefore undulated, these cells carry cilia (fig. 18 A). Farther on the duet widens considerably
and at different points the folds of the wall become so deep as to touch each other;. so narrow
tubes are formed, running parallel to each other. Several of these tubes are compactly filled
with spermatozoa, ven- regularly placed with their heads directed towards the wall and their
tails directed inwardly. In these tubes the cilia have disappeared; only the median part of the
cloaca-duct preserves the cilia, amongst which there are a great number of strongly staining
granules (fig. 18B). Close to the point where the cloaca-ducts bend for the second time, they
narrow again and are reduced to their former shape. A pretty strong circular muscle surrounds
this part of the cloaca-ducts. It appears to me that this extension of surface should perform
the function of vesicula seminalis, whilst other appendages may be looked upon as receptacula
seminis. These consist of two spacious bags, connected with the cloaca-ducts by short canals.
In this there is affinity with Dondersia festiva (Hubrecht 3) and Ismenia ichthyodes (Pruvot 4).
The wall consists of cylinder-epithelium with oval nuclei at the basis, strongly ciliated. In these
bags numerous spermatozoa, dispersed in every direction, are found ; for the rest I do not
consider a secretory function impossible. Copulation probably takes place : two strong copulation-
spicula are present.

The wal! of the precloacal organ is formeel as in the other Neomenidae and as that oi
the end-funnel of the cloaca-ducts of Chaetodcrma (Wirén 6a). The precloacal organ is small
and opens into the cloaca through a small opening (fig. 5).

The above mentioned copulation-spicula are in communication with the cloaca in the
nart indicated 1>\ c (fig. 19—21, 7 — 9 es). Their direction is proximal above the ventral nerve-
stems and they extend to some distance anteriorly (cf. Proneomenia vagans, Kow. and Mar. 2).
They are either round organs, triangular or somewhat square, apparently calcareous. Such a
calcareous spiculum is surrounded by a firm distinctly staining cuticula ; around this a layer
of epithelium-cells is found. Regarding its formation the following facts should be mentioned.
cellular envelopment increases in bulk considerably at the basis of the spiculum ; here the
cells become high and cvlindrical and are of a peculiarly threadlike structure (fig. 20b). In this
epithelium-bag is enclosed a cuticular mass (fig. 20c") which is continuous in the attenuated
cuticular layer around the spiculum. This mass is very finely fibrillar, the fibres being in continuity
with those of the cells of the bag. Upon this mass a little column d is found, built up of cells
and continuous in a very transparent part, in which some nuclei are perceptible. This transparent
column is not long; around this we find the basis of the proper spiculum, of which after
decalcification nothing is visible. Moreover the spiculum is sustained at the basis by a hard
ring t\ which is structureless and stains obviously. An attenuated circular muscular layer a
surrounds it entirely. The relation between the said parts and the calcareous spiculum cannot
be discovered. To the basis of the spiculum are attached long strong protractors (cf. fig. 19)
enveloping the spiculum and attaching themselves to the clistal body-wall ; (fig. 21 A, p~] and
also strong but shorter retractors, fixed to the ventral and lateral body-wall (/'). Fig. 2 1 B
shows the shape of a copulation-spiculum, after isolation with Eau de Javelle.

We must not overlook the presence of a pre-anal gland around the cloaca (fig. 6 — 8),
the structure of which may be compared with that of Proneomenia neapolitana (Thiele 8).

Examination of the heart can be properly made when this is in diastole at the death
of the animal. The median walls of the pericardial prolongations invaginate (fig. 22 A); these
invaginations increase in size and as soon as both offsets have united, the invaginations coalesce
and form together the atrium (fig. 22 B, a). This atrium, which has consequently a distinct
doublé origin, is open distally and dorsally. Then there is also a ventricle : an invagination ot
the pericardium, with trucker wall (C, v). This interpretation of atrium and ventricle is the more
justifiable on account of two points of communication between both, which can be indicated ;
at those points the wall is much thicker and apparently forms a sphincter (D). The same
arrangement obtains in other Solenogastres, which I hope to describe afterwards. In other forms
atria are also demonstrated (Hubrecht 2). To me it seems that it should be interpreted in this
way : the heart of the Solenogastres is undergoing marked reduction, a reduction running parallel
to that of the gills and gill-veins ; an opinion also enunciated by Thiele. This opinion is
preferable to that of Heuscher (5), who considers the heart of Proneomenia Sluiten to be in
an embryonic condition. It must be owned that the facts hitherto known concerning the structure
of the heart cannot be Iooked upon from one point of view ; close investigations, especially
in comparison with Chaetoderma, are very desirable.

Of the circulatory system I only mention the dorsal sinus, which takes its course
proximally for a considerable distance and is also found distally to the pericardium ; besides
two lateral sinuses, originating in the distal offset of the animal.

No doubt we have to do with a species of Proneomenia. This species chiefly differs from
the type of the genus in its radula, salivary glands, cloaca, cloaca-ducts, copulation-spicula and
shape of the body. It cannot be classed among either of the ten known species of Proneomenia.

2. Proneomenia longa nov. spec. (Plate i figs. 23 — 40).

Stat. 211. 5°4o'.7S., I20°45'.5 E. Near the isle of Saleyer. 1158 M. 2 Specimens.

Length-index 37 — 50. Colour varying from yellow-white to light brown. Posterior end
elongated trunk-shaped as it is in Proneomenia Weberi. Numerous pointed spicula in many
layers upon each other in a thick cuticle. Papillae large and vesicular. Radula polystichous,
up to 24 rows ; the teeth of the middle-rows are broad, the others are long, either pointed,
clubbed or hooked. 2 Long salivary glands, which remain separated. Cloaca-ducts each provided
with vesiculae sem.inales and a vesicular receptaculum seminis. 2 Large copulation-spicula or
numerous small ones.

East-Indian Archipelago. 1 Specimens.

Each of the specimens has to be treated separately.

The length of the first specimen is 62 mm., the diameter 1.25 mm. The length-index
is therefore 50. The colour is white, somewhat yellowish, glittering owing to spicula, intercrossing
rectangularly. The ventral groove is distinctly visible. The hinder part is elongated as is the
case with Proneomenia Weberi, though in a slighter degree (cf. fig. 23).

The spicula are of the ordlnary shape, but they are a little larger than those of
Proneomenia Weberi ; they lie often flat against the body-wall. Along the ventral groove and
around the cloaca-opening spicula like those of fig. 3 B and D are found.

The whole of the tolerably thick cuticle is beset with spicula in many layers upon
each other. Numerous papillae pierce the cuticle; they belong to the multi-nucleated type and
are met with upon thick stalks. The full-grown papillae are vesicular, round, with some nuclei
at the base, surrounded by cytoplasma, which extends along the wall of the vesicle and also
travels through the vesicle in fine threads. The stalk shows several nuclei and is of a threadlike
structure. The papillae only appear after the formation of the stalks ; young papillae are never
found in the immediate vicinity of the hypodermis, but always more towards the outside of the
cuticle ; thus nearly all the papillae are situated at one level. At the end of each stalk a
little knob is formed, multinucleated and with strongly granular cytoplasma ; in a more advanced
stage the knob increases in size and openings occur in the cytoplasma ; when full-grown the
cytoplasma together with the nuclei removes to the wall, only to traverse the vesicle in a
threadlike shape. At last the vesicles break though the cuticle and open (fig. 25).

A dorso-terminal sense-knot is present.

The ventral groove and folds are like those of Proneomenia Weberi. The 'klimmer-

höhle" is spacious and divided into two halves by a median fold, suspended from the dorsal wall.
That wall consists of high cylindrical epithelium with round nuclei and very granular cytoplasma ;
it carries long cilia. The "hintere Bauchdrüse" is only strongly developed around tlie "Flimmer-
höhle", where the glandular cells extend as far as the dorsal part of the pharynx. In a similar
stage of developmenl at that place is the "vordere Bauchdrüse" with its crystalline glandular cells.

The mouth-cavity contains numerous cirrhi, here also filled with sreen granules. The
" Mundleisten" present the following divergence : they do not travel along the wall of the
mouth-cavity, but they traverse the latter in strings, so that they take their course directly
ventrally and cut off a coecum, filled with cirrhi to the right and the left (fig. 24).

When comparing fig. 27 with fig. 13 it becomes evident at once that here the strong
folds, separating in Proneomenia Weberi the mouth-cavity from the pharynx, are absent, as
well as the folds of the oesophagus. For the rest the salivary glands are similarly placed here ;
the situation of the radula also coincides. It is different with the structure of the radula. As
usual much has been injured in the cutting and consequently a great deal cannot be inferred
from the transverse sections. Fig. 26 gives a transverse section. Here it is clearly visible that
the radula is polystichous ; the number of the teeth is about 24, but there are also several
free teeth, the origin of which cannot be traced. The two middle-rows are occupied by broad,
fiat teeth, presenting some layers, staining in different degree. The other teeth are rather long,
straight and slightly clubbed or hooked. Fig. 27 represents the course of the radula: first
proximally passing out of the radula-sac then bending ventrally, once more distally surrounded
by pouch b. This is an epithelial pouch; the radula enters it and folds its borders, in transverse
sections the pouch being therefore completely filled with teeth (fig. 28). Both large, flat teeth
are thus placed against the dorsal wall ; the other walls are beset with the numerous other
teeth of which in fig. 28 only a few are given to prevent confusion. The basal-membrane which
connects the teeth with each other, is distinct. More distally in the pouch, the radula teeth
soon disappear and the epithelial pouch alone remains. In the lumen a grey, extremely finely
granular mass is found, which probably has filled the whole of the pouch, but has lost its
connection with the wall by fixation. In this mass there are a few round bodies (fig. 28). Here
we have the same arrangement as in Proneomenia Weberi; in the pouch most probably a
cuticular secretion takes place, perhaps necessary for the strengthening or reparation of the
radula-membrane. The radula itself cliffers from that of Proneomenia Weberi by the shape of
the teeth and their number.

For the rest the intestine does not furnish much worthy of note. The wall of the rectum
is ciliated and merges gradually into the cloaca-wall ; this is characterized by the change of the
epithelium. The cubical ciliated epithelium of the rectum is only preserved at the dorsal wall; at
the lateral wall the epithelium becomes high and cylindrical with round nuclei, and pro'vided
with cilia.

The nervous system is of a structure entirely similar to that of Proneomenia acuminata.
Wirén 6b pag. 81).

The animal is mature. Large eggs, full of volk and with a strong membrane are also found
in the pericardium. The genital glands which extend only a very little distance proximally

'v/

contain eo-o-s formed at the meclian wall and spermatozoa formed at the lateral wall. The
structure of the efferent canals fully corresponds to that of Proneomenia Weberi (fig. n).
Only the cloaca is of a simpler structure (cf. figs 5 — 9 with figs 30 — 35). Fig. 5 corresponds
to fig. 30 ; here also at b is an invagination of the body-wall, carrying spicula which here are
curved, whereas the papillae are broader and the vesicular knob is much less visible. Only
the precloacal organ opens out more proximally, this being therefore not visible is fig. 30.
The following figures 110 Jonger correspond. Here we observe that the cloaca does not form
the proximal coeca a, c and <ƒ, but only «, into which merges the rectum, its epithelium having
been noticed above. The wall of the cloaca is built up of ciliated cylindrical epithelium. More
proximally this changes into a multicellular epithelium (fig. 38); the cells are glandular and
accumulated, the wall containing therefore in a more or less degree papillae ; the whole gives
the impression of glandular epithelium with cilia. Along the median part of the dorsal wall
runs a strongly ciliated band of epithelial cells. At the lateral cloaca-walls the epithelium is
different (fig. 39) : regularly granular, ciliated, strongly staining cells alternate with more
transparent cells, carrying no cilia. This tissue strongly resembles that of the cloaca-wall of
Chaetoderma (Wirén 6a, Taf. \T fig. 9), though with respect to-this absolute certainty cannot
be obtained. The possibility of this tissue being also present in this animals cloaca-wall should
of course not be excluded, whilst in the other Xeomeniidae it is only to be found in the wall
of the precloacal organ, this being here also the case. The two copulation-spicula are built as
in Proneomenia Weberi.

The structure of the heart may be compared with that of Proneomenia Weberi. On
both sides of the median walls of the pericardial offsets, part of the wall is also invaginated,
which invaginations fuse into one atrium. In this atrium the original doublé origin may very
easily be recognized (fig. 36). Here too the ventricle is an invagination of the dorsal pericardial
wall, of very small extent first, but larger more proximally. The atrium is in continuity with
the ventricle, the latter being still very small; here are also two atrio-ventricular openings, both
of them closed by a little sphincter. Only one of the openings is visible in fig. 36. The blood-
sinus, with the exception of the dorsal one, are very clifficult to follow.

The length of the second specimen is i~ mm.; its diameter 1 mm.; the length-index
therefore 37. The colour is not yellow-white but light brown. For the rest the appearance is quite
the same as that of the first specimen. The structure of the interior also coincides. The radula-sac
is very distinct (fig. 37). The radula-teeth are still delicate and curved in the sac ; in cutting
they are therefore generally touched at two pointe. The formation takes place simultaneously
with that of the basal membrane, which does not differ from the teeth in consistency.

The only real difference between the two specimens lies in the copulation-spicula. Fig.
40 gives a section through the hinder part of the body and may be compared with a section
between figs 32 and 33. Here it is seen, that not one copulation-spiculum is found on either
side, but that there are several : 5 to the left and 8 to the right. They are small spicula,
surrounded by a thin cuticula and sheath, built up of cubical epithelium. Each is provided with
its own muscular bundies. They open out into the cloaca at the ventral wall, before the cloaca
opens to the exterior.

SIBOGA-EXI'EDITIE XI.VII.

IO

In my opinion both forms are to be classed in one species, the one point of difference
not outbalancing the very important resemblance.

This species is doubtless closely allied to Proneomenia Weberi. The shape of the body,
the inteo-ument, the cloaca-ducts with appendages, the heart and the copulation-spicula present
many points of conformity; buth the length-index, the structure of the radula and the cloaca
differ in many respects.

The principal points of difference from the type of the genus are found in the structure
of the radula and of the cloaca-ducts, and in the presence of copulation-spicula.

3. Proneomenia sp. (PI. II figs 57 — 59).

Stat. 87. o°32'S., iiq°39'.SE., near Palos-bay, W. Celebes. 655 M. In mud. 1 Specimen
(fragment).

A fragment of 1 mm. high and broad. The appearance of this posterior extremity is like
that of Proneomenia Weberi. The specimen must be mentioned on account of the structure ot
the cloaca-ducts. Fig. 57 represents a reconstruction of the interior organs. Regarding this the
following should be noticed. The cloaca is a simple cavity, without proximal offsets. Gradually
its slightly ciliated epithelium changes into the higher strongly ciliated epithelium of the rectum.
Laterally the cloaca is continuous with two small coeca (a). The course of the cloaca-ducts is
normal. The portion, running proximally carries cilia, but is without the vesiculae seminales ot
the foregoing species. Both parts of the cloaca ducts, proceeding distally. remain separated
(fig. 59). They do not unite into the precloacal organ. The epithelium is rather cubical and not
ciliated. Where they curve, the cloaca-ducts are continued into the coeca ó, uniformly structured;
other appendages are absent. Shortly before their opening out into the cloaca, both ducts
coalesce, but the unpaired portion is very small (0.05 mm.). Of the well-known tissue of the
precloacal organ nothing is perceptible. In other forms this arrangement also obtains in more
or less.degree. Thiele observed (8) in Proneomenia neapolitana that the cloaca-ducts coalesce,
the epithelium of the united part remaining low, not being glandular either. In his opinion
there is some relation between this condition and the animal's immaturity. In my specimen the
genital glands are small and no production of genital material takes place. Here also the slight
development of the cloaca-ducts might go together with the immaturity of the animal. This
also Kowalewsky and Mariox noticed for Lepidomenia hystrix (2) and Pruvot for Proneomenia
vagans (4). However Thiele makes mention for the mature Notomenia clavigera (9) of two
glandular cloaca-ducts opening to the exterior separately, but not into the cloaca. For Strophomenia
izei Pruvot describes (10) two fully developed cloaca-ducts with appendages, opening out
severally into the cloaca. The possibility of the ducts remaining separated in this case too is
not excluded, but it is also possible that we have to clo with a young specimen. The structure
of the cloaca points towards that of Proneomenia longa, though there is not complete similarity
between the two. Fiere too the cloaca-spicula are wanting but perhaps they only develope in
maturity. Further, to the right and left, a copulation-spiculum is present, cross-shaped or more
triangular, with a delicate cuticular sheath. Very distinct are the dorsal and ventral blood-sinuses,

1 1

the latter being enclosed by muscles running horizontally and ventrally; besides two
lateral sinuses.

It is much to be regretted that the anterior end of this excellently preserved specimen
is wanting. Now it cannot be decided with certainty where to place this form.

Dinomenia nov. gen.

Length-index 11 — 20. Spicula pointed, hollow, in many layers above each other in a
thick cuticle. Papillae numerous. A dorso-terminal sense-organ is present. Three ventral folds.
Two unramified tubular salivary glands, which remain separated. Radula distichous. Cloaca-ducts
with vesicular appendages. No gills.

4. Dinomenia Hubreckti nov. spec. (PI. II, figs 41 — 56, PI. IV, fig. 113).

Stat. 202. 3°I5'S., I25°43'.8 E. In horizontal cylinder. 3088 M. 1 Specimen. (See Conclusion).
Stat. 310. 8° 30' S., 1190 7'. 5 E. Between Sumbawa and Flores. 73 M. Upon Gorgonid.

Length 14 — 16 mm. Length-index 11 — 13. Body rather pointed at both extremities.
The mouth-cavity and the opening of the pharynx separated by a fold. Considerable accumulations
of unicellular glands around the pharynx. Five rows of radula-teeth. Two stalked vesicular
vesiculae seminales and two stalked vesicular receptacula seminis. Two copulation-spicula.

East-Indian Archipelago. 2 Specimens.

The length of the hrst specimen is 16 mm.; the diameter 1,25 mm.; the length-index
therefore ±13.

The length of the second specimen is 14 mm.; the diameter also 1.25 mm.; the length-
index therefore ±11.

The colour is brown-yellow, somewhat shining owing to the spicula. The posterior and
anterior extremities, both ending rather bluntly, are difficult to distinguish from one another.
The ventral groove is clistinct (fig. 41).

The spicula are shaped like those of Proneomenia Weberi (fig. 42 A). Besides along
the ventral groove long, thin, curved spicula and flat massive ones are found (B). In the
tolerably thick cuticle the spicula are lying in many layers upon each other. The state of
preservation does not permit of the structure of the integument being studied. The papillae,
present in great number, are vesicular with many nuclei, placed upon broad, multinucleated
pedicles. Here the mode of growth also corresponds to that of Proneomenia longa : first the
pedicle grows out, at the end of which a little knob appears with some cells; this knob increases
in size and becomes vesicular. Very seldom, and then mostly in the posterior region of the
body, a papilla occurs opening externally. The papillae may grow so large, that they rise as
little round protuberances above the surface of the cuticula ; even then they clo not burst open,
but remain closed.

The ventral groove runs as far as the cloaca. The ventral fold represents one large
fold, on either side of which another very small one is found. The "Flimmerhöhle" is spacious

I 2

an,l divided into two halves by a median fold of the dorsal wall. In the (listal portion of the
"Flimmerhöhle" the wall is built up of cylindrical epitheliurn with long cilia and strongly granular
cvtoplasma. More proximally this epitheliurn changes into a cylindrical epitheliurn, carrying cilia,
hut staining with difficulty, and remaining very transparent; the nuclei are spindle-shaped and
the cells are of a thread-like structure. This region produces a secretion, similarly clear and
transparent. This is the "vordere Bauchdrüse" with its secretion, which is found around the
orcans everywhere in the anterior part of the body. The "hintere Bauchdrüse" is also well
developed and its pear-shaped, glandular cells, staining bright red with carmine are found
among those of the "vordere Bauchdrüse".

A very small dorso-terminal sense-knot occurs at the very hinder extremity oftheanimal.

The alimentary canal furnishes some peculiarities, cf. fig. 43, reconstructed out of trans-
verse sections, and the schematic sections figs. 44 — 47. The cavity a may apparently be
compared with the mouth-cavity of the other Neomeniidae. Here the numerous cirrhi occur
again and also the ciliated "Mundleisten". However the cavity does not lead directly into the
pharynx: the proper entrance into it is found in cavity b. Both cavities a and b are separatecl
from each other by a fold (fig. 45^)- It does not give the impression that this fold occurs
here casually ; a strong muscle proceeding transversally is found in this fold ; moreover a number
of muscular fibres, taking their course diagonally, attach themselves to it. I look upon the
tolerably perfect separation between the anterior part of the mouth-cavity, which carries organs,
and that part, in which the opening of the pharynx is found, as an arrangement, the animal
can use at will. Cavity b does not carry any organs.

The pharynx itself has a thin folded wall ; it runs dorsally and takes up a wide coecum,
directed proximally, the wall of which is folded too. An extremely thin circular muscular laver
surrounds the wall of the pharynx.

The radula may easily be discerned. It consists of about 5 rows of teeth behind each
other. Such a row consists of two large teeth; fig. 49 A represents a whole tooth; B is the
upper side of another tooth, C its lower portion. It is evident that regarding the exact structure
of the teeth no perfect certainty is obtained. This radula however is distinct distichous, every
row consisting of two teeth of shape A, operating as a pair of scissors. So that there is an
affinity with Paramenia, Lepidomenia and Ismenia. But in none of these forms does the radula
seem to be so strong as it is here, where about 5 pairs of such strong radula-teeth occur.

The typical distichous character of the radula is evident from the radula-sac ; in following
the radula in distal direction we reach the radula-sac, consisting of two pouches, in each ot
which a tooth is formeel ; only more proximally a single radula-sac originates from the coalescence
of these two pouches (fig. 50).

The radula teeth are placed upon an epithelial layer with round nuclei, tolerably strong
muscles attaching themselves to this. Immediately close to it the salivary glancls open out; they
are long and take their course ventrally from the intestine (fig. 48). To the right and left ot
the radula-sac some large cartilaginous cells are found (fig. 4;<r), serving for support to the
above mentioned muscles. Around the two salivary glands and against the wall of the intestine
a peculiar glandular tissue is found : unicellular strongly granular glands, grouped in lobes. They

begin directly behind the point where the salivary glancls originate, and extend a considerable
distance distally. Any opening of these glands cannot be discerned (fig. 113).

Fig. 43 shows that the pharynx distally from the radula narrows considerably and
suddenly passes into the intestine, without first forming a separate oesophagus. The intestine
itself does not furnish much worthy of note; from my transverse sections the folds are very
difficult to tracé. The rectum opens out dorsally into the cloaca.

With regard to the nervous system hardly anything can be mentioned, the state of
preservation not being such, as to admit of this. Sublingual ganglia cannot be indicated
with certainty.

The genital glands only extend a little distance proximally. Genital products are not
present. The situation of the organs in the posterior part of the body is represented in the
reconstruction fig. 5 1 . The cloaca-ducts take a normal course, unite and form the unpaired
precloacal-organ. Where they curve the cloaca-ducts are continued into a coecum, with the same
structure as the glandular portion of the precloacal-organ itself. The appendages are remarkable.
First a long tube is observed at the end of which there is a pouch, stretching far distally and
situated against the body-wall (fig. 5 1 a). Into the part of the cloaca-ducts proceeding proximally a
small tube opens, leading into a specious pouch with attenuated wall (b), built up of cubical
epithelium. In neither of these appendages are spermatozoa found (cf. figs. 52 — 55).

Two copulation-spicula occur in the cloaca (fig. 5i«); they are long and run dorsally,
their ends being therefore situated dorsally to the rectum. They are not purely calcareous;
after decalcification there remains in the sheath a cuticular mass, having in many places round
openings, it being therefore quite possible, that not one large spiculum is found here, but
several smaller ones, situated next .to each other, a phenomenon we also remark in Paramenia
Pruvoti. (Pruvot 4 pag. 774).

The heart is of a peculiar structure, though not everything about it is clear to me.
In fig. 56 some of the sections are represented. Beginning distally it is seen from A that the
dorsal pericardial wall is invaginated («), more proximally this invagination becomes bilobed,
and next to it another invagination originates (B, b). Both a and b unite and form one large
invagination (C, b -)- a), this portion of the heart being therefore in some degree trilobate.
D represents this portion of the heart, which has lost its connection with the pericardium-wall
more proximally and is lying free in it. The shape is more or less triangular. More proximally
still the heart divides into two halves (E.) ; both parts regain their connection with the dorsal
pericardial wall, and appear as invaginations of it. How to explain those different invaginations?
This cannot be done with certainty: a and b might be atria. But what may be the ventricle
in that case? If the invaginations c are to be taken for it, then the ventricle is distinctly doublé,
which is possible, but has not been met with as yet. Then atria and ventricles would be situated
the one behind the other, a situation also found elsewhere. But this interpretation cannot be
sustained with certainty, the structure of a, b and c being exactly alike. Only an accurate
comparison with other forms can procure us a good insight into this.

What is indicated in fig. 56 A by d, also visible in the following figures is a peculiar
accumulation of cells, with large, oval nuclei, staining obviously. Probably these cells carry cilia.

'4

They may be compared with the "bourrelet cilié" which Pruvot gives for Proneomenia vagans
<4 fig. 60). Here however nothing is perceptible of a "gouttière" formed by this band and the
heart itself and serving for the passage «f the spermatozoa; the "bourrelet" always remains
here at a certain distance from the heart, and the pericardial wal] between both is by no
means deepened. The band proceeds towards the point, where the cloaca-ducts pass out of
the pericardium.

The question now arises where to place this form. It cannot be classed in any of
the genera known up to now. On account of the distichous radula it departs from Proneomenia,
the lattcr having always a polystichous radula. It might be compared with Paramenia, but from
this genus it differs by the structure of the integument and the absence of gills. I look upon
this form as a new genus. The structure of the integument and of the radula is of the greatest
si^niricance for the Solenog-astres. In these characteristics it differs from it closest relations, the
genera Proneomenia and Paramenia, with each of which it has one characteristic in common.
Therefore it is to be regarded as intermediate between both ; it is related to Proneomenia
because of the integument and to Paramenia on account of the distichous radula.

5. Dinomenia verrucosa nov. spec. (PI. II, figs. 60 — 75, PI. III, figs. 76 — 82).

Stat. 50. Badjo-Bay, W. coast of Flores. Upon Hydroïd. 40 M. 1 Specimen.

Stat. 164. i°42'.5 S., I30°47'.5 E. Between N. Ceram and New-Guinea. 32 M. 1 Specimen.

Stat. 260. 5°36'.5S., I32°55'.2E. Near the Kei-Islands. 90 M. 2 Specimens.

Stat. 289. 90 o'. 3 S., I2Ó°24'.5E. S. E. coast of Timor. 112 M. In mud. 6 Specimens.

Stat. 310. 8° 30' S., 1 1 g° 7'-5 E. To the N. of Sumbawa. Upon Hydroïd. 73 M. 1 Specimen.

The dimensions vary considerably : full grown specimens may obtain the length of 98 mm.
The integument is provided with many prominences. The cirrhi in the mouth-cavity are united
into bundies. Radula with many rows of teeth. The salivary glands spring from two ventral
pouches of the pharynx. A great number of stalked receptacula seminis (or vesiculae seminales).
Xo copulation-spicula.

East-Indian Archipelago. 11 Specimens.

One of the specimens has been represented in hg. 60, drawn from life, in natural size.
The length is 98 mm.; average diameter 6.25 mm.; the length-index being therefore ió.
Proximally the animal is broad and rather bluntly truncated ; more distally it becomes thinner
and terminates rather pointeclly. The mouth-slit is slanting. The ventral groove is distinct but
narrow. Colour: orange-red with bright violet prominences, irregularly dispersed all over the
body, only absent on the ventral side. This specimen is full-grown.

A nother young specimen is represented in fig. 61 enlarged four times. The length-index
of the other specimens varies from 9 to 20, a considerable difference ! But the length-index
may be said to be 16 — 20, the one specimen of the length-index 9 showing some deviations,
probably not being quite normally developed. Outwardly the different specimens also differ
considerablv. The animals are either hVht or dark brown, sometimes with reddish end, sometimes
with lighter prominences. Only the largest specimen (fig. 60) is of the above-mentioned two
colours, and has to be regarded as the most fully developed; the other specimens, though

15

often mature, are probably not fully cleveloped. While they were alive, I could at least in none
of them detect the two said colours, though all the specimens show the prominences in more
or less degree. The interior structure however takes away every doubt regarding amnity.

The cuticle is thick, especially in the foremost and hinder portion ; in the middle region
of the animal it is comparatively much thinner. It is traversed by many layers of spicula. The
prominences are formed by a thickening of the cuticula. The spicula are of the usual shape
(fig. 62 A), but are comparatively small and of unequal size. On the prominences they are
somewhat larger. The cuticula being thicker there, and the large spicula mostly standing erect,
the prominences are immediately conspicuous. The spicula of shape B and C are found along
the ventral groove.

There are numerous papillae upon long stalks, not dilating vesicularly. On the prominences
they are especially numerous and accumulated, a fact, giving rise to the question whether perhaps
any special function has to be attributed to the prominences.

A dorso-terminal sense-organ is present; tolerably strong muscular bunclles surround it,
by means of which it can probably be stretched and retracted. Around this very small, slightly
curved spicula are arranged.

Around the cloaca-opening, where the body-wall forms a shallow furrow, special spicula
are also found (fig. 62 D) in considerable numbers, whilst there the papillae are numerous too
and of a somewhat different shape.

Behind the "Flimmerhöhle" the ventral fold has five folds, or rather three, the middle
and larger one being in some specimens more or less distinctly divided into three : there being
in that case five folds. More distally there are only three folds (fig. 81). Just before the cloaca-
opening the ventral folds terminate. The "Flimmerhöhle" is not spacious. The folded wall is built
up of strongly ciliated cylindrical epithelium ; amongst its cells those of the "hintere Bauchdrüse"
are seen to open out; these are also found all along the ventral groove. The "hintere Bauch-
drüse" is not so strongly cleveloped as it is in other forms: it only encircles the "Flimmerhöhle"
but does not extend around the pharynx. The "vordere Bauchdrüse" is not present, at least
cannot positively be demonstrated. Here and there among the other glandular cells crystalline
cells are found, reminding of the cells of the "vordere Bauchdrüse" of the other Neomeniidae.

The cloaca is of a simple structure. It is a more or less heartshaped space, opening on
the ventral side of the animal through a narrow slit. The wall is strongly folded and lined
throughout by a strongly ciliated cylindrical epithelium, with oval nuclei. The cloaca divides into
two parts: the dorsal and larger portion giving entrance to the rectum, the ventral and smaller
one to the precloacal organ (fig. 79 a and 6).

The digestive canal furnishes the greatest peculiarities, see fig. 63. The wide mouth-slit
leads into the large mouth-cavity. Very strong "Mundleisten" occur, whilst cirrhi are found in
space a. These are arranged in bundies. Each bundie is placed upon a small epithelial fold ; so
that there are a great many bundies isolated from each other. Some of the cirrhi of these bundies
have one common base, some stand free from each other. In some specimens the green granules
of which we spoke in Proneomenia Weberi are met with. The "Mundleisten" are strongly built
and entirely filled with connective tissue. Further there still remains to be mentioned a little

i6

coecum running proximally in the mouth-cavity (b), present in nearly all specimens. Besides
there occur folds (c), ventrally suspended trom the dorsal wall. This wall is very minutely folded
and provided with a strong cuticle ; the ventral wall behind the mouth is ciliated.

The transition into the pharynx is gradual. The latter is round, with strongly folded
wall and encircled by vigorous circular muscles (m). On the dorsal side the wall is built up
of cylindrical epithelium with delicate cuticle. The pharynx unites with the proximal coecum; the
part originating trom this coalescence is a wide tube, the whole of which is coated by strongly
cuticulated epithelium ; the wall is minutely folded, which folds grow larger on the ventral side.
A little coecum (d), directed distally, is present.

Both widely separated salivary glands take their origin in the ventral wall. They show
the following peculiarity: there are two tubes (e) proceeding distally, the wall of which is strongly
folded and constituted ot rather cubical epithelium. Against the wall an obviously staining mass
is situated, which may reach such an extent, as to fill the folds. I look upon this mass as a
secretion from the tubes (hg. 64c). YVhen looking at figs. 63 and 64 we observe that these
tubes pass into narrower ones (s g), formed like the salivary glands of other Neomeniidae ;
they take their course ventrally from the intestine. These are the salivary glands, which therefore
do not open out directly into the pharynx, but through the above-mentioned wide tubes c. In
none of the Solenogastres known until now has this been observed, nor has it been mentioned
of Proneomenia australis (Thiele 9).

Behind the salivary glands the radula is founcl. The pharynx has already attained here
a tolerable width and has the character of the intestine. An oesophagus cannot be distinguished
here. The radula is more or less curved and ends in the radula-sac r. The radula is well
cleveloped and of a distinct distichous character (figs. 65 — 69). lts structure cannot be thoroughly
examined. Any perfect similarity between the difterent specimens does not exist. Fig. 65
represents the teeth of the largest specimen. A is a tooth from the radula itself, B a fullgrown
tooth from the radula-sac ; for the rest there are fragments of teeth, which of course occur in
various other shapes. In another specimen the same shape is met with as represented in fig. 65
together with pointed curved fragments (fig. 66). Fig. 67 however shows more comb-shaped teeth.

All these shapes may be reduced to one type, viz. that of fig. 65 A. These teeth are
arranged in two rows (fig. 68) upon a very strong basal membrane (b). In the radula-sac the
formation of the teeth is seen simultaneously with that of the pedicles c by which the teeth
are supported. The distichous character of the radula is clearly visible from the radula-sac ; it
is noticed that the teeth are formeel in two separate sets in connection with each other and
lined with one continuous epithelial layer, vet remaining separated. Moreover fig. 69 represents
the radula at the point, where it bends into the radula-sac: there are two rows of teeth severally
separated by an epithelium fold, folded in such a manner with respect to the teeth, as to make
the latter exactly fit into it. The radula-sac is alternately directed proximally or distally, there
being apparently some relation between its direction and the state of contraction of the intestine.

In one specimen, the one of the length-index 9, a radula cannot possibly be demonstrated,
but the structure of the digestive canal corresponds to that of the other specimens.

The intestine takes a normal course; the septa are very regular and alternate with strong

muscular bundies, running dorsoventrally. The animals feed on Alcyonaria, the remains of
which are easily discernible and found in great numbers in the intestine.

When examining fig. 70, a reconstruction of the anterior part of another specimen, a great
difference is noticed from fig. 63. Yet there is also a correspondence between the two, considering
that in fig. 70 the state of the digestive canal is due to the walls of the mouth-cavity being
stretched and the pharynx being contracted, whilst in fig. 63 on the contrary the walls of the
mouth-cavity are contracted, the pharynx being stretched. If we suppose in fig. 63 the walls
of the mouth-cavity are stretched, then the pharynx takes a different position : it is invaginated
into the mouth-cavity; thus the ventral wall of the pharynx is drawn ventrally and the radula
and salivary glands change their position. The digestive organs in the anterior region of the
body are very movable, which explains the important differences in the transverse sections.
The structure of the radula and salivary glands however offers decided points of similarity.

The rectum with its strongly ciliated wall gradually merges into the cloaca. The latter
is a vertically placed slit, which widens proximally and gradually takes the shape of a heart ;
the dorsal part (a) passes into the rectum, the ventral and smaller part (6) into the precloacal
organ (fig. 79).

Fig. 78 shows a reconstruction of the uro-genital organs, out of transverse sections oi
a young animal. In full-grown specimens the pericardium is so large as often to cover the
other organs; it is for this reason that I chose a young animal. Figs. 79 — 82 give schematic
sections through the posterior end of another specimen, comparable with the lines A B — G H
of fig. 78. The one thing worth noticing are the appendages of the cloaca-ducts ; they are
round pouches, connectecl with the cloaca-ducts, where these bend, by narrow tubes. In mature
specimens they are filled with spermatozoa. The wall consists of cylindrical epithelium, which may
become cubical when the vesicles are filled with spermatozoa and therefore dilated. 'The number
varies considerably : very young specimens have none at all, whereas I counted in one mature
specimen on both sides about 20. The specimen of fig. 78 is so young that the cloaca-ducts
are still separated ; yet it has already the receptacula seminis. A similar arrangement also
obtains in Proneomenia australis (Thiele 9).

The heart greatly resembles that of Proneomenia Weberi. .Here again both atria are
already formed before the coalescence of the pericardial offsets ; in one specimen they are even
already entirely closed (fig. 81). After the atria have united, the doublé character is still
recognisable. The ventricle is again an invagination of the dorsal pericardial wall and in some
specimens a doublé communication is discernible between atrium and ventricle.

Reo-ardine the nervous svstem the only thing to be mentioned is, that though both
lateral nerve-stems are connected by a commissure with the two ventral ones in the distal
body-region, yet the commissure between both lateral sterns (ganglion posterius superius), above
the rectum is wanting.

The question arises, whether we have not to do with Proneomenia australis, of which
Thiele gives a short description (9). The length-index of the latter is 18; the cirrhi of the
mouth-cavity are arranged in bundies ; remains of Alcyonaria are found in the intestine; the
receptacula seminis are present : all of them points of resemblance. Points of difference are :

SIBOGA-EXPEDITIf. XI.VII.

iS

i" The radula of Proneomenia australis is biserial, not distichous, the radula-teeth are rather
straight, long and conical; these forms I do not meet in Dinomenia verrucosa.

2° The salivarj glands in Proneomenia australis are long tubes, situated ventrally from the
intestine. A peculiar condition like that ot Dinomenia verrucosa is not mentioned by Thiele.

; l'hr cuticle of Dinomenia verrucosa shows very conspicuous prominences, also occurring
in young specimens.

To me all these seem to be sufficiënt points of difference to consider these animals a new species.

When afterwards the very incomplete account of Thiele has been replaced by more accurate

information, it wil) be seen, whether this view is correct or not.

Xo doubt this species, as well as the preceding, is related to Proneomenia on account

of the structure of the integument, but is also related to Paramenia on account of the

distichous radula. Nothing prevents us trom arranging this and the preceding form under one

genus. The presence of copulation-spicula in only one of both species does not interfere with

this arrangement : Proneomenia presents a similar difterence.

Proparamenia nov. gen.

Length-index 12 — 20. Cuticle thick with many layers of pointed spicula and with
numerous papillae. Dorsal sense-organ absent. 3 Ventral fokls. A circlet of gills in the cloaca.
No copulation-spicula. Radula monoserial. 2 Ramified salivary glands, remaining separated.
2 Vesicular receptacula seminis.

6. Proparamenia bivalens nov. spec. (PI. III, figs. 83 — 100).

Stat. 320. 6° 5' S., II4°7'E. Java-Sea. 82 M. In fine grey mud. 2 Specimens.

Length 18 — 31 mm. Spicula more or less S-shaped. Number of gills about 20.
2 Specimens in the Java-sea.

Both specimens are in a rather poor state of preservation. One of them is represented
in fig. 83, enlarged 4 times. The colour is brownish-yellow, here and there greyish ; the
anterior part is more or less reddish. The animal is somewhat shining owing to the spicula:
the latter are thin needies interlacing in various directions, amongst vvhich the papillae show
through as dark points. The ventral groove is clistinct and along the whole of its course the
spicula are placed in the same direction. Cloaca-spicula are not cliscernible.

The length of the first specimen is 31 mm., the diameter 1.5 mm.

The length of the second specimens is 18 mm., the diameter 1.5 mm. The length-index
varies therefore from 12 — 20. As neither of the two specimens can be considered mature, the
normal length has probably not been reached, the length-index being thus of doubtful value.

The cuticle is strongly cleveloped, especially at both extremities, and entirely beset with
spicula, in numerous layers upon each other. The spicula are easily recognisable by their S-shape
fig. 84 Ai; those of shape />' are found along the ventral groove. The papillae are numerous
and large; thev are multi-nucleated and placed upon thick pedicles.

19

A dorsoterminal sense-knot cannot be indicated.

The ventral groove runs as far as the cloaca and contains 3 folds : 1 large median fold
and 2 smaller lateral ones. The "vordere Bauchdrüse" cannot be demonstrated. The "hintere
Bauchdrüse" is only slightly developed, except around the "Flimmerhöhle". A very rigorous muscular
bundie connects the dorsal wall of the "Flimmerhöhle" with the dorsal body-wall (fig. 85, m).

The characteristics of this form are found in the structure of the alimentarv canal and mlls.

Fig. 87 gives a reconstruction of the anterior part of the alimentarv canal. The mouth-
cavity is spacious, filled with unramified long cirrhi ; the " Mundleisten" are comparatively small.
The part next to it, which may be called pharynx, is a long tube, the wall of which is strongly
folded, the lumen being therefore extremely small. It is encircled by a strong circular muscular
layer, numerous unicellular glands opening out into it.

A well developed radula is present (fig. 88). Passing out of the radula-sac it runs
dorsally; then it bends to take a somewhat slanting ventral direction, on account of which it
can be touched twice in the transverse sections (fig. 89). Radula-teeth are met with of pointed
shape (fig. 88 C), or with two points (A), more comb-shaped (B and E), or consisting of two
parts above each other (F). B may be a fragment of F, and A, C and D fragments of E.
Shape E gives the impression of being an uninjured tooth. There is only 1 row of teeth, the
radula being therefore monoserial. A distinct basal membrane carries the teeth (fig. 89). I
consider this interpretation the most acceptable; perfect certainty however cannot be obtained.
Fig. 90 e. g. represents a section through the radula-sac with 1 tooth, almost of shape F.
But small pieces (r. t.) are moreover found in the radula-sac, lying quite lose from the saicl
tooth. Whether these are fragments or not cannot be decided. Shape A reminds of a tooth
entirely different from F but is probably a fragment; from the transverse sections however can
only be concluded that there is but 1 row of teeth. The radula is placed upon a far projecting
tongue, coated with cubical epithelium and filled with loose connective tissue ; under the radula
however the epithelium is multi-layered (fig. 89). The radula-sac is surrounded by a circular
muscular layer, from which muscular bundies originate, running towards a number of cartilaginous
cells (fig. 90, cc), also mutually connected and enveloped by muscles. These cartilaginous cells
are very transparent and partly or entirely filled with greenish granules sometimes travelling
through the cells as bands.

The salivary glands, which remain separated, spring from the lateral pharyngeal wall,
in front of the radula. They are of a peculiar structure and consist of different globular
accumulations of glandular cells : narrow cells, strongly granular. Here and there a small lumen
is discernible in the globules. They produce a secretion which flows into a canal, by which it
is conveyed to the pharynx, the wall of which consists of cubical epithelium; a tolerably strong
circular muscular layer surrounds it. These canals — the salivary ducts (fig. 87 s.d.) — are ramified
several times and end therefore in some blind oftsets (fig. 86 s. d.). How the matter, secreted
by the glandular portion finds its way to the tubes, is not clear, probably between the cells
of these. To a certain extent this arrangement also obtains in Rhopalomenia aglaopheniae
(Pruvot 4, fig. 46). were lobes of glandular cells surround the salivary glands, here unramified;
the opening out of the cells into the ducts is not exactly indicated (cf. fig. 92).

20

The pari next to the radula, is of a similar structure. It finally unites with the proximal
dorsal coecum which is of considerable size, to form the intestine. We cannot speak of an
oesophagus, the whole region from the mouth-cavity to the intestine having the same structure
throuo-hout. This is also evident trom the glands, merging into it evervwhere : they are strong,
pear-shaped glands, opening out between the cells of the pharynx (fig. 91).

In <>iie of the species the intestine is entirely filled with remains of food, showing clearly
that it feeds on animal-food (small Vermes r), even on animals of tolerably large size ; the alimentary
canal is ven elastic, which is also confirmed by the strongly folded wall of the pharynx.

\s ïvards the nervous system, I will only mention that the commissures between the
ganglion posterius superius and the ganglia posteriora inferiora are absent.

Fig. 93 gives a representation of the structure of the generative organs and of the
pericarclium, figs. 94 — 99 representing schematic sections. The structure of the cloaca-ducts
corresponds to that of Proneomenia Weberi; the receptacula seminis are stalked vesicles, but
the vesiculae seminales are absent. Both specimens are young, the generative organs are not
vet fully developed, whence a uniform structure of the cloaca-ducts and the absence of a
glandular part. Both cloaca-ducts coalesce and the precloacal organ merges into the cloaca,
which enwraps it in two folds (fig. 95). The coalescence of the cloaca-ducts and the presence
of the receptacula seminis prove the animals to be half-grown. The cloaca itself is a wide, open
space, narrowing proximally.

W'hat is of great importance is, that in the cloaca gills are found, 20 in number (fig. 94).
They are strongly folded evaginations of the cloaca-wall, coated with cubical ephithelium and
strongly ciliated. They are very full of blood-corpuscles ; at the base of each gill-fold a large
blood-sinus is present. For this reason it presents great affinity to Paramenia siërra and impexa
Pruvot 4). It is without doubt here that the gills are not evaginations of the rectum- wall as
is the opinion expressed by Wirén for Neomenia, (Wirén 6b), cf. figs. 94 — 96; it is seen that
the rectum merges into the cloaca far more proximally, the cloaca-wall of the interjacent region
hcing smooth and without gills (fig. 95). Muscular fibres, running in every clirection connect
the gill-carrying epithelium with the body-wall. Around the gill-folds numerous sharply borderecl
blood-sinuses are met with; more proximally all these sinuses unite into a few large ones
f114. 95); more proximally still there are only 4 sinuses: 1 on either side of the intestine and 2
dorsally from the pericardium, leading the blood from the gills directly into the heart (fig. 96).
The latter is composed of an atrium and a ventricle. Fig. 100 gives 5 sections through
the pericardium and through the heart. In A the two pericardial offsets are seen, not vet
united; the two invaginations going to form the atrium more proximally, are distinct; in each
of them one of the above-mentioned gill-sinuses opens (g. s.). B shows the atrium large and free
from the dorsal pericardial wall (a). In C the ventricle appears, in connection with the atrium
through an opening; the wall of the ventricle is thick (D) and only far more proximally (E)
it is proved to be an invagination of the dorsal pericardial wall. The dorsal blood-sinus is
already visible in E.

The place of this form is difficult to fix. The bocly-investment resembles that of Proneo-
menia, as well as the radula (cf. Proneomenia neapolitana, Tiiiele 8, fig. 78). But in Proneomenia

2 I

gills never occur. These are only met with in a few forms, viz; in Pruvotia sopita, Macellomenia
palifera, Paramenia impexa ancl siërra, and Neomenia. From Pruvotia it is clearly distinct by the
possession of radula and salivary glands. From Paramenia impexa it greatly differs by the presence
of 2 salivary glands and ot a monoserial radula. Stronger is the resemblance to Paramenia
siërra, where the dorsal salivary glands are absent. It considerably differs from Macellomenia
palifera with its monoserial radula, the structure of the salivary glands and of the integumént
being entirely different.

Still in other respects e. g. as regards the shape of the spicula, and the structure of the
cloaca-ducts and cloaca there is a difference between this form and Pruvot's Paramenia. Pruvot
gives the following characteristic for the genus Paramenia: a thick cuticle ("cuticula crassa", 4,
pag. 724). Regarding this the following must be noticed : the cuticle is not thick: for Paramenia
impexa Pruvot does not give a description of the cuticle, but as we can learn from his fig. y?,,
the cuticle is anything but thick, whilst for Paramenia siërra he admits, that the cuticle is
rather thin (10, pag. 483). Simrotii rightly mentions the thin cuticle as being characteristic
lor the genus Paramenia (7, pag. 232).

The Neomeniidae may be arranged into 2 groups :

1" Forms with thick cuticle, with numerous pointed, hollow spicula in different layers and
provicled with a great number of hypodermal papillae.

Neomenia Tullberg.
Proneomenia Hubrecht.
Rhopalomenia Simroth.
Pruvotia Thiele.
Strophomenia Pruvot.
Dinomenia nov. gen.
(?) Notomenia Thiele.

2" Forms with thin cuticle, covered with a layer of flat, imbricated spicula, without hypodermal
papillae.

Dondersia Hubrecht.
Lepidomenia Kow. & Mar.
Ismenia Pruvot.
Myzomenia Simroth.
Macellomenia Simroth.
Nematomenia Simroth.
Stylomenia Pruvot.
Echinomenia Kow.

Paramenia (Pruvot) may be called intermediate between the two groups : Paramenia impexa
approaches more closely group 1, Paramenia siërra group 2.

Proparamenia offers more points of comparison with the first group : the cuticle is
thick, the spicula, disposed in many layers, are of the Proneomenia-shape and the papillae are
numerous. Por this reason as well as on account of the monoserial radula it seems to me

22

rationa! to separate Proparamenia and Paramenia, even though there is some affinity both on
account of the structure of the salivary glands and the gills. The name Proparamenia has been
chosen in order to indicate in some measure the doublé relation.

Rhopalomenia.

-. Rhopalomenia indica nov. spec. (PI. III, figs. 101 — 112).

Stat. 5. j° 4.6' S., 114° 30'. 5 E. N. E. coast of Java. 330 M. In mud. 4 Specimens.

Stat. 47. Bay of Bima (Sumbawa). 55 M. Upon Gorgonid. 1 Specimen.

Stat. 162. Betweel] Loslos and Broken-islands. W. coast of Salawatti. (W. coast of N. Guinea).

18 M. 1 Specimen.
Stat. 253. 5°48'.2S., I32°i3' E. To the West of the Kei-Islands. 304 M. Upon Gorgonids.

8 Specimens.
Stat. 262. S°53'.8S., I32°48'.8L. To the West of the Kei-Islands. 560 M. Upon Gorgonids.

6 Specimens.
Stat. 289. 90 o'-3 S., I26°24'.5E. S. E. coast of Timor. 112 M. In mud. 6 Specimens.
Stat. 305. Between Flores and Lomblen. 113 M. Upon Gorgonids. 2 Specimens.

Length-index 9 — 26. 2 Long salivary glands, which remain separated. A great number
of receptacula seminis. Cloaca in a superficial groove.
East-Indian Archipelago.

This animal is of frequent occurrence and of very variable dimensions. The length varies
from 11 — 39 mm., the diameter from 1 — 2.5 mm., the length-index from 9 — 26. This great
dirïerence in size must probably be attributed to the animal being either mature or not. The
external appearance is the same : terminating rather pointedly. The colour is brown, but sometimes
more yellowish or darker (figs. 101 — 103). The ventral groove is distinct. The integument
is glittering owing to the interlacing spicula. In some of the specimens the pharynx has been
evaginated out ot the mouth-slit.

The spicula are of the ordinary Proneomenia-shape : they are straight or curved and
hollow (fig. 104 A). Around the cloaca-opening spicula of shape C are found, and along the
ventral groove those of shape B '. The structure of the integument too points directly to the
relation with Proneomenia or Dinomenia : the cuticle is thick, with many layers of spicula. Each
spiculum is formed by 1 cel!, fitting round the base of the young spiculum. The numerous
papillae are multicellular.

The dorsal sense-organ is distinct and may be compared with that of Proneomenia
Sluiteri (Hubrecht i, fig. 11); the nerve, from which it is innervated, is also visible.

The ventral groove runs as far as the cloaca and contains 1 large median fold and
2 smaller lateral ones. The "vordere Bauchdrüse" is strongly developed ; its clear finely fibrillar
cells are met with everywhere in the anterior body-region around the pharynx.

The cloaca-opening is found in a kind of furrow ; this furrow, either deep or shallow,
is lined with a cuticle, in which numerous flat spicula are implanted; these are placed parallel
ti' each other and are slightly bent (fig. 104 C); in this part papillae are absent (fig. 108 c. g.).

The specimens differ chiefiy from the preceding species in the structure of the digestive

or^ans. In fio-. 109 a reconstruction of the anterior part is given. The cirrhi and „Mundleisten"
are entirely filled with green granules, also met with in Proneomenia Weberi. The pharynx is
lono- and narrow, with folded wall and built up of slender glandular cells. A circular muscular
layer surrounds the pharynx; besides it is encircled by numerous accumulations of pear-shaped
glandular cells (cf. Rhopalomenia aglaopheniae Thiele 8, pag. 268, fig. 117). The pharynx
opens into the spacious intestine, which is provided with a large proximal coecufn. It is here
that both salivary glands merge into the pharynx separately; they are long and composed of
cubical epithelial cells, surrounded by a layer of glandular cells of equal thickness (tig. 112).

Of a radula or radula-sac no tracé can be found.

In some specimens the pharynx has been entirely evaginated out of the mouth-slit. In
that case the salivary glands and sublingual ganglia are found outside the mouth situated upon
the evaginated pharynx.

The intestine with its regular coeca, between which dorso-ventral muscular bundies take
their course, and the rectum opening out into the dorsal part of the cloaca, do not present
any peculiarities.

The structure of the cloaca-ducts presents the principal points of similarity with Dinomenia
verrucosa. Fio-. 10=; oives a reconstruction of this end. It is obvious that there is much resem-
blance with fig. 78. In this full-grown specimen the receptacula seminis are very large and
entirely filled with spermatozoa. The reconstruction of the receptacula seminis is taken from
nature in order to show the shape of the pouches and their situation. Their number varies
considerably according to the more or less advanced stage of development of the animals ; in
fig. 105 it is about 13, a number which may still increase.

Copulation-spicula are absent.

The cloaca is a tolerably small cavity with irregularly folded strongly ciliated wall ;
gills are entirely absent.

After what has been stated for Proneomenia Weberi the heart does not furnish anything
worthy of note.

What has been noted for Dinomenia verrucosa regarding the nervous system holds good
here: the commissure between both lateral sterns (ganglion posterius superius) is wanting.

This form undoubtedly strongly resembles Proneomenia Weberi. But it should remain
distinctly separated from it for the absence of a radula; therefore it has also to be kept distinct
from Proneomenia thulensis (Thiele ii) and australis (Thiele 9), which have similarly formeel
cloaca-ducts.

We must arrange this form uncler the genus Rhopalomenia, allied to Proneomenia but
distinguished from it by the absence of a radula. From Rhopalomenia aglaopheniae Kow. &
Mar. it differs in the structure of the salivary glands and the cloaca-ducts.

8. Rhopalomenia debilis nov. spec. (PI. IV, figs. 114 — 1 1 7 1.

Stat. 204. 4°2o'S., 1220 58' E. Northern entrance of Buton-strait. 75—94 M. Upon Gorgonid.

1 Specimen.

Length-index 8. 2 Long salivary glands, which remain separated. Rudimentary radula-sac,

24

considerably enlarged and dividing into 2 tubes. Separated cloaca-ducts without appendages,
the only specimen being very young.

East-Indian Archipelago. 1 Specimen.

A very smal! animal, measuring 6 mm.; the average diameter is 0.75 mm., the length-
index therefore 8. The animal is represented in fig. 114, 4 times enlarged. The colour is brown.
The ventral groove is distinct. The animal is shining owing to the fine spicula.

,\ short description of the specimen is sufficiënt. It quite coincides with the preceding
species. This holds good for all the organs, with the exception of the cloaca-ducts and the
pharynx. Here we have to do with a young specimen; the generative organs do not function as
vet; the cloaca-ducts are separated and have a thin wall ; the receptacula seminis are absent.
All these divergences may be a consequence of the immaturity of the animal. Too much
importance should not be attached to differences, occurring in these organs.

2 Points of difference should be observed :
1" The furrow in which the cloaca-opening is found, is absent here.

2° Besides the two salivary glands the pharynx has another appendage, a fact of more impor-
tance, cf. figs. 115 and 116, sections through the anterior part of the body. In fig. 116
the pharynx has united with the proximal coecum of the intestine ; the two salivary glands
(«) merge into the pharynx more proximally, but are free in fig. 116 and take a normal
course. The walls are thick and of a similar structure to those of Rhopalomenia indica
(cf. fig.. 112). Further a small tube b is obvious, opening out into the pharynx more proxi-
mally. More distally (fig. 115) 6 divides into 2 tubes, running parallel to the salivary
glands but ending much sooner. They are of a curious structure : the wall presents a limited
number of rows of square cells, enclosing a lumen, and not perfectly fitting together ; here
and there something is contained in the lumen (fig. 1 1 7), viz : some granular globules, which
however gives the impression of being parts of the cells, not a secretion. In many Soleno-
gastres 4 salivary glands occur. The ventral ones are long tubes, 2 in number, as in
Proneomenia, merging into the pharynx either separately or united : these are the tubes a
in figs. 1 1 5 and 116. 4 Tubular ventral salivary glands have never been observed : only
2 ventral and 2 dorsal ones (cf. Paramenia impexa).

These tubes b might also be compared to the ampullae of Rhopalomenia aglaopheniae
Pruvot 4, fig. 44 — 46) but the shape of the latter is round and by no means tubular, whereas
they open out separately.

A third point of comparison might be presented by the radula-sac, the situation of
which corresponds to that of other forms, and which might be rudimentary here. When e. g. a
radula disappears the radula-sac no longer functions as such ; when increasing in size it may
have the appearance, which is shown here and obtain another function. To me this seems to
be the best interpretation ; it points at the same time to its having originated from a form
with distichons radula (cf. the radula-sac of Dinomenia, figs. 48 — 50, 65 — 69). This suggestion
is the more justifiable on account of the fact, that in Rhopalomenia aglaopheniae a rudimentary
radula-sac also occurs (Thiele 8, pag. 267).

25

Hemimenia nov. gen.

Closely related to Neomenia, from which it differs in the structure of the integument.
Leno-th-index 7. Spicula flat, imbricated; no papillae; cuticle thin. Carina with many pouches,
filled with large lance-point-shaped spicula. 1 Ventral fold. 1 Pair of vesiculae seminales and
1 pair of receptacula seminis. Communication between the precloacal organ and the penis-
spicula. No copulation-organ.

9. Hemimenia intermedia nov. spec. (PI. IV, figs. 118 — 140. PI. V, figs. 141 — 145).

Stat. 49!'. 8°23'.sS., 1190 4'. 6 E. Sapeh-strait (between Soembawa and Flores). 69 M. 1 Specimen.
Stat. 114. o° 58'. 5 N., 1220 55' E. Entrance of Kwandang-Bay, N. Celebes. 75 M. 1 Specimen.

Length 14 mm. Colóur yellowish-brown. Carina distinct, ]/16 of the body-height. Number
of "Hls 20. 6 — 10 Abdominal spicula on each side.

2 Specimens from the East-Indian Archipelago.

The length of the iïrst specimen is 14 mm., the average diameter 2 mm.; the length-
index therefore 7.

The second specimen is too much shrivelled to determine the length-index with any
accuracy.

The animal is pale yellowish-brown and of a silvery brightness (fig. 118). The ventral
groove is distinct; the mouth- and cloaca-opening are visible as little round depressions. The
ventral part looks like that of Neomenia grandis (Thiele 8, fig. 1 a). A sharply lined carina is
present, 0.4 mm. high. Viewed from the dorsal side, it is flat and several round or oval dark
spots are distinctly visible (fig. 119).

The small spicula have a flat spatula-shaped appearance, with strong border; the middle
portion is thin ; they are imbricated (fig. 1 20 a, f). Among them there are also found long
thin spicula, sometimes bent, often with curved points, but few in number (c, d, e). All along
the ventral groove however, they are arranged profusely. On the carina a third form is detected,
viz. large, firm lance-pointed spicula (è). These are found at the above mentioned spots on the
carina. Such a round spot proves to be a little cavity, entirely filled with these spicula. In Neomenia
these spicula are also found in small numbers (cf. Wirén taf. II, figs. 3 — 6), and especially in
Neomenia grandis (cf. Thiele 8, fig. 2 a) ; in this species they are only situated on the carina.

I could not demonstrate any special spicula round the mouth- or the cloaca-opening, as
I decalcifiecl the specimens before making the sections.

The cuticle is thin, as compared with the hypodermis (fig. 121); its thickness never
exceeds half of that of the hypodermis; as it is traversed throughout by the very numerous
spicula, only a ver)- thin layer remains. The hypodermis on the contrary is thick and appears
to me to consist of two layers of cells ; two rows of nuclei are seen one above the other ;
sometimes the contour of the cells, clasping each other wedgewise, is visible too, but my sections
do not give any positive certainty regarding this point (fig. 121).

SIBOGA-EXFEDITIE XLVII.

26

Papillae are entirely absent, which was to be expected, the cuticle being too thin. In
this Hemimenia differs greatly from Neomenia. The layer oi hypodermal cells is of unequal
height indeed; sometimes thread-like offsets from the hypodermal cells penetrate into the cuticle,
but formation of papillae does not take place everywhere.

In the small pouches upon the carina the structure differs. There the thickness of the
hypodermis is onl) one cellular layer, whereas the cuticle is thicker than the hypodermis (hg. 122).
Sometimes the pouches are more or less divided into two by a longitudinal median fold of the
hypodermis (figs. 14c) — 141). Here also papillae are absent, but the hypodermal cells have
offsets, which pierce the cuticle; these offsets are either broad or very thin and often provided
at the end with a little transparent knob (hg. 122). This might be considered as a papilla, but
tbr its great difference from the proper papillae of Xeomenia. In the thick cuticle of the
] louches the lance-point-shaped spicula are implanted, amongst these thin cuticular columns are
situated, usually ending in a little knob. The function of the pouches is not clear, though they
have probably to be regarded as a sense-organ.

The ventral groove is distinct, but very narrow and proceeds to a place close before
the cloaca. On either side of the ventral groove a kind of lip is found (cf. Tiiiele 8, pag. 224).
There is some difference between Hemimenia and Neomenia in there being only 1 ventral fold
and not 7 or 9. This ventral folcl is large and broad. The epithelium of the ventral groove and
ventral fold carries cilia in the posterior portion. The "vordere Bauchdrüse" with its transparent
very finely fibrillar cells and the "hintere Bauchdrüse" are both well developed.

We should not overlook the organ, described by Thiele as "abdominal spicula", by
Wirën as "finger-shaped glands". Fig. 135 shows some openings, round or oval-shaped (a. s.)
to the right and left of the ventral fold. They are short hollow tubes, lined with cubical epithelium
and opening to the exterior more distally. It is a moot point whether they are spicula or a
gland ; the tubes are entirely or partly filled with some cuticular matter. They give the
impression of being spicula and not glands. Their number is for the first specimen 6 on each
side, for the second on one side 8, and on the other side 10. These numbers are much smaller
than those found in Xeomenia.

A dorso-terminal sense organ, as indicated for Xeomenia grandis, is absent.

The diaphragma is absent, which was also the case in Xeomenia grandis.

The nervous system fully corresponds to that of Xeomenia carinata (Wirën 6i> pag. 66,
fig. 6 B). The commissures between the ganglion posterius superius and the ganglia posteriora
inferiora take a peculiar course; they wind their way between the penis-spicula and cloaca-ducts,
ventrally to the intestine (figs. 138 — 140).

The following is noticed with regard to the structure of the alimentarv canal. A longitudinal
section through the anterior region of the first specimen is represented in fig. 123, with which
correspond the transverse sections of figs. 124 — 130. The mouth-cavity is not spacious ; the
lateral and dorsal walls are beset with cirrhi; more or less arranged into bundies and ramified
at the base. The "Mundleisten" are in the shape of a horse-shoe. In fig. 124 at b is a coecum
of the pharynx, directed proximally; at a is a transverse fold of the epithelium. Fig. 125 shows that
the coecum b is one continued whole with the mouth-cavity, and represents the two folds of a.

After the mouth-cavity comes the pharynx, a long rather straight tube. The ventral
wal! has a fold c (fig. 126). The pharynx is entirely surrounded by strong circular muscles,
amongst which however muscular fibres diverge in different directions ; p and / are similarly
encircled by muscles. In transverse sections the pharynx is cross-shaped (fig. 127). Distally the
pharynx narrows and is continuous with the proximal coecum d\ at the ventral wall the fold ƒ is
found, full of connective tissue and muscular fibres. Fold f carries two other smaller folds g,
which in fig. 1 30 are no Jonger in connection with ƒ, whilst f is loose from the pharyngeal wall.

In order to establish the resemblance to Neomenia, compare fig. 123 with Wirén's fig. 1,
taf. IV, (6b). There are some points of resemblance e. g. the mouth-cavity with the cirrhi, and
the proximal coecum {d - = Sh). The proboscis of Neomenia carinata may be present here in
folds ƒ and />, but both „Schlundleisten" (S L) are lookecl for in vain. Neomenia microsolen
offers points of affinity ; Neomenia Dalyelli, in which the „Schlundleisten" and proboscis are
absent, offers even more. Thiele's description of Neomenia grandis is not quite clear; there is
probably more resemblance between Neomenia grandis and carinata than between Neomenia
grandis and Hemimenia. We cannot however be too cautious in making comparisons, the state
of contraction of the pharynx being of much importance. This is confirmed by the second
specimen, the pharynx of which is quite straight, wide at first but very narrow further on ;
the folds b and c are absent ; f is present but very small. In this specimen numerous glandular
cells are met with around the pharynx and among the pharyngeal muscles ; pear-shaped cells
arranged in groups and opening into the pharynx. In the first specimen nothing of all this is
perceptible. For Neomenia grandis Thiele has figured similar glands but much less developed.

The intestine is large and broad and jorovided with regular coeca. In the anterior part
it is exclusively constituted of ciliated epithelium ; more distally cilia are only to be indicated at
the dorsal wall. The intestine is entirely surrounded by a thin muscular layer. The animal feeds
on sponge ; in one of the specimens the alimentary canal is filled with rests of food, amongst
which there are numerous sponge-spicula. The short strongly ciliated rectum has a folded wall.

Figs. 131 — 139 show the structure of the cloaca. In fig. 131 the cloaca is open ventrally;
in fig. 132 the ventral walls are slightly closed, which is more obvious still in fig. 133. In
fig. 1 34 the cloaca is closed ventrally and divides into two, the closing lips having united
dorsally from the penis-spicula. In that way 2 cavities are formed : the large dorsal one a
and the smaller ventral one b. The cavity a is clothed by cubical ciliated epithelium and leads
into the rectum (fig. 134). Fig. 134 represents the 2 cavities c uniting more proximally into
one large cavity (fig. 135). The latter is an opening in the connective tissue surrounding the
organs, without any proper wall, rendering it possible for the precloacal organ to be movable.
Blood-corpuscles are not contained in it. In fig. 137 it is seen that the precloacal organ opens
out into cavity b, ancl therefore into the cloaca. From a comparison with Neomenia carinata
it is evident that the "Vorhof" of Wirën is here a very narrow tube, provided with strong
muscles, and built up of strongly ciliated epithelium (b). This difference is of special importance,
a copulation-organ being absent here. Hence there is some resemblance to Neomenia Dalyelli.
The ventral part of the cloaca b does not carry gill-lamellae.

In the dorsal cloacal portion the gill-lamellae are found. Their number is about 20, a

2 8

considerably smaller number than observed in Neomenia. They are of various sizes; from smaller
single folds to larger ramified ones. 'They are filled with blood-corpuscles, which are either
round or oval-shaped and very large with oval nuclei and yellowish cytoplasma. Around the gills
there is a compact, dense tissue, which Wirën designates in Neomenia carinata with the name of
blood-gland. Lacunae are observed in it, permitting the blood to flow from the adjacent tissue
into the gill-lamellae. Around the blood-gland no special blood-sinuses are to be demonstrated ; the
blood circulates through the loose connective tissue. In fig. 131 — 133 the red lines ƒ represent
the course of the blood and not the presence of a special circular blood-sinus. The blood,
flowing trom the gills through the blood-gland and the connective tissue accumulates in some
sinuses, dorsally to the cloaca (fig. 132 — 135), by which it is directly led into the atrium.
This atrium has originated from the union of 2 invaginations of the distal pericardial offsets,
and has therefore a doublé origin ; the ventricle is an invagination of the dorsal pericardial
wall (fig. 137). Probably there are also 2 atrio-ventricular openings. Of the blood-sinuses the
dorsal and ventral one are to be mentioned, the large nerve knots and the rectum being also
surrounded by blood-lacunae (figs. 123, 136, 137). In Neomenia carinata and Dalyelli the atrium —
(it is better to say atrium than gill-vein) — is single (Wirën, 6b, pag. 56), though Wirén believes
it to be the coalescence of 2 parts as also appears from his figure 5, plate VIII and from
fig. 7, plate IX. In Neomenia grandis the atrium is single.

The genital glands do not present anything noteworthy. The animals are fully mature ;
eggs and spermatozoa occur in great numbers. The part of the cloaca-ducts passing out of the
pericardium, is a straight tube with folded wall, built up of ciliated epithelium, surrounded by
a strong circular muscle (fig. 138). This part is connected with a spacious bag, with non-ciliated
wall and similarly encircled by a muscular layer (fig. 140 vs-\-d). These pouches (fig. 139^. s.)
are entirely filled with spermatozoa, the heads of all of them being directed towards the wall.
They probably are vesiculae seminales and may be compared to the ampullae of Neomenia
grandis (Thiele 8, pag. 240), the latter however being of the nature of widenings of the
cloaca-ducts in Neomenia carinata (Wirén 61', plate VII, fig. 2 B). The cloaca-ducts first proceed
proximally in the shape of wide tubes filled with spermatozoa, to bend afterwards and to run
distally. At the point of bending a thin winding tube is found, i to the right and 1 to the
left, leading into a large receptaculum seminis, a spacious bag of cubical epithelium and filled
with spermatozoa (fig. 143).

The precloacal organ is large (fig. 138). A copulation-organ is entirely absent as is the
case in Neomenia Dalyelli. The precloacal organ is of the usual structure, only the end, opening
into the cloaca, has a wall composed of cubical ciliated epithelium. The genital products passing
from the precloacal organ into the cloaca (ó) are not directly ejected but are also met with
in part a of the cloaca (fig. 133 o v).

The portion of the cloaca-ducts taking its course distally, is provideel with an appendage,
not present in Neomenia. To make this clear I must first mention the penis-spicula ("strang-
förmige Organe" Wirén; "cordlike organs" Tullberg-, "penis-spicula" Thiele). Their course is
shown in figs. 133 — 140. Here too, they consist of a "ïinnenförmige" and "pfriemförmige" bar,
running parallel to each other. The penis-spicula protrude into the cloaca, where both bars

unite into one (fig. 145 A). In fig. 145 both the situation and the shape of the two bars is

represented. Probably the bars consist on the outside of cuticular matter, remaining after

decalcification, and staining faintly with carmine ; the inner part appears to me to have been

calcareous. The bars may also be hollow (cf. Thiele 8 fig. 47). Each bar is encircled by a

cubical epithelial layer, which is likewise surrounded by muscles : protractors and retractors.

( )f a common epithelial layer surrounding them nothing is perceptible. The glands belonging

to the penis-spicula are well developed. In fig. 135// they are seen (violet) on the point of

opening into the covering of the penis-spicula; their course is represented in figs. 136 — 140.

Fig. 139 shows a small vesicle g, connected with the precloacal organ by means of a little

tube (fig. 138); g and // unite into one large vesicle g -f- h (fig. 140), increasing in size more

proximally and dividing into lobes, as in fig. 142 it has been touched more than once. This

is undoubteclly the gland of the penis-spicula, described by Wirén and Thiele. Fig. 144 B

represents the structure of its wall : long strongly granular glandular cells, ciliated and with

oval nuclei (a) ; at different points the granules increase considerably in number and stain

intensely with carmine, the whole of the cells becoming dark-red (6). These granular cells are

especially tound in vesicle g. After g and // have united this difference becomes evident, but

more proximally cells, more granular, are intermixed with cells less granular. Here and there

the cells open and the granules are discharged into the lumen of the gland. What kind of

organ may this be ? Wirén and Thiele look upon the penis-spicula as being in some way

connected with the copulation, a view which to me too seems correct ; the function of f

however cannot be made out. The spermatozoa from the precloacal organ might pass throuo-h

g and // and then go to the penis-spicula; the name of the latter would be the more justifiable

on this account. Besides its secretory function the gland might also perform the office of

vesicula seminalis, the size and width of the gland favouring this view ; the .secretion mio-ht

procure enveloping matter for the spermatozoa. This may to a certain extent also explain the

fact of the spicula being hollow. Evidence against this view is the presence of numerous

spermatozoa in the precloacal organ, whereas in g they are entirely absent. Another inter-

pretation is this; in the gland a secretion is formed, partly conveyed to the penis-spicula, partly

to the precloacal organ, which is confirmed by the presence of obviously staining granules in

the precloacal organ and in tube g.

Hemimenia is, no doubt, closely related to Neomenia. Yet I feel justified in considering
it another genus on account of the structure of the integument, which differs very considerably
from that of Neomenia. Neomenia belongs to the forms with thick cuticle, pointed spicula and
papillae, (group 1 pag. 21), Hemimenia to those with thin cuticle, flat imbricated spicula,
without papillae (group 2). It is therefore a transition-form and as such may be compared
with Paramenia.

Cyclomenia nov. gen.

Length-index 7. Shape of the body cylindrical, proximally bluntly truncated, clistally
narrower and more pointed. Dorsal sense-organ present. Cuticle thick. Spicula pointed and in

30

many layers. Papillae almost entirely absent. 3 Ventral folds. Radula distichous, very large;
broad bands with small teeth, close against the pharyngeal wall. Radula-sac very spacious and
invaeinated. 2 Globular salivary gdands, without lumen or efferent canals. Cloaca-ducts without
appendages, hut winding and considerably widened. 3 Small copulation-spicula. A circlet of gills
in the cloaca.

10. Cyclomenia holosericea nov. spec. (Plate Y figs. 146 — 171).

Stat. 300. io°48'.6S., [23 23'.! E. E. coast of Rotti, to the west of Ti mor. In fine grey mud.

918 M. 1 Specimen.

about 20.

Length 1 3 mm. Bronze-coloured with dark ring at the anterior part. Xumber of gills

o.

1 Specimen trom the East-Indian Archipelago.

It is represented in fig. 146, 4 times enlarged. The length is 13 mm. At the anterior
end the diameter is 2 mm., at the posterior end 1,5 mm.: average diameter 1.75 mm. The
length-index is therefore about 7. The shape of the animal is cylindrical ; the sections are
perfectly round ; hence the name. The anterior extremity is broad and bhmt at the end. The
ventral groove is distinct, the mouth-opening slit-like. The colour is dark grey, somewhat greenish
or bronze. At the anterior end a dark ring is noticed. The animal is not shining, but velvety;
spicula are not visible.

The spicula (fig. 147) are of the Proneomenia-shape : hollow, straight or S-shaped (A);
along the ventral groove they are broad, though thin and very transparent (B).

The cuticle is rather thick and transversed by spicula in various directions (fig. 148).
The hypódermis is only 1 cell thick and consists of narrow epithelial cells, with finely
granular or fibrillar cytoplasma ; often the cells are broader in which case they are transparent.
A spiculum originates from 1 cell, which afterwards surrounds it as a little cap. The spicula
remain in connection with the hypódermis by thin threads, met with everywhere in the spicula.
Papillae are absent. In fig. 164 on either side (/>) a little knob appears, formed by a protraction
of the hypódermis and the muscles of the body-wall. By these knobs a superficial ventral furrow
is bordered. Here the cuticle is slightly thinner, whereas the hypódermis forms transparent or
extremely minute knobs, upon thin stalks (fig. 150).

The cuticle is covered throughout with a thick layer of dirt, which hides the spicula
from view and causes the velvety appearance.

A dorso-terminal sense-knot is present on the terminal extremity of the animal.
The ventral groove runs from behincl the mouth as far as a little way before the cloaca-
opening and has one large median fold and two smaller lateral ones. The " Flimmerhöhle" is
spacious and divided by a dorsal wall into a left and a right half (fig. 152): the wall carries
very long cilia. The "hinten- Bauchdriise" is very strongly cleveloped, especially around the
"Flimmerhöhle"; its granular, deeply staining glandular cells extend on either side of the pharynx ;
more distally the gland becomes less developed, though still discernible. Amongst its cells all

around the pharynx numerous round or pear-shaped glandular cells are found, with round nuclei
and finely granular cytoplasma. These are probably the cells of the "vordere Bauchdrüse", but
this cannot be determined with certainty.

The structure of the alimentary canal in the anterior part of the body furnishes the
«reatest peculiarities. Fig. 150 gives a reconstruction ; the schematic sections figs. 151 — 157
correspond to the lines A B — NO. The mouth-cavity is large, but partly filled with the fold ƒ
of the dorsal wall. A great number of ramified cirrhi are present; "Mundleisten" are absent.
Distally from the fold /", the mouth-epithelium is strongly folded and ciliated. The mouth-cavity
leads into the pharynx, similarly provided with a folded ciliated wall in the anterior region ;
more distally the shape of the pharynx becomes more round or irregularly oval-shaped (fig. 152).
More distally it widens considerably.

2 Salivary glands merge into the pharynx; they are globular organs (fig. 153 sg.),
consisting of long granular glandular cells with round nuclei. A lumen is wanting, but between
the glandular cells small openings and slits occur, enabling the secretion to flow into the
pharynx. In fig. 154 it is seen that the pharynx is going to divide into a large ventral part
and a smaller dorsal one; the latter is separated from the first and leads into the intestine
after having united itself with the proximal coecum (fig. 155). This coecum is large, with
strongly folded wall, more proximally divided into different parts (hg. 153). The pharynx is for
some length continued into the intestine as a deep fold, the folds p closing ventrally from the
pharynx (figs. 155 and 156).

Very remarkable are the radula and the radula-sac. Figs. 154 — 156 show the folded
wall of a in the lumen of the pharynx b. More distally in fig. 156 it is seen that the dorsal
walls of a and b unite; in fig. 157 it becomes clear that a is an invagination of b. Thus the
distal and dorsal wall of the ventral portion b of the pharynx is invaginated. The wall of b is
built up of cubical epithelium (fig. 158). The structure of a is different: fig. 158 shows that the
wall is peculiarly folded ; the dorsal folded wall partly consists of cubical, partly of cylindrical
epithelium with oval nuclei and strongly fibrillar cytoplasma. It is by these walls that the radula
is formed. The latter is an exclusively cuticular formation : a basal membrane with some teeth,
attached to the radula-sac in crypts. The teeth are more intensely stained with carmine than
the basal membrane itself, but undoubtedly the basal membrane and teeth form together one
mass. More proximally the walls of a and b approach and are lying side by side ; the radula
therefore being surrounded by epithelium on either sicle. Now the radula loses its connection
with a and attaches itself to b, the teeth thus coming free. From there the radula is pushcd
along the pharyngeal wall in a dorsal direction. The radula is very strongly developed. Along
both the lateral pharyngeal walls to a place close before the mouth-cavity the tvvo broad
radula-bands are found. Fig. 159 shows a section through the pharynx; the wall is composecl
of cubical epithelium, becoming higher more dorsally (a) and presenting more or less vesicular
cells. The lateral walls are completely covered with the radula, which is flat with a few teeth.
A similarly large radula has not vet been observed for Solenogastres. In fig. 150 the contour
of the radula is indicated by a red line; in the pharynx the radula is 0.7 mm. long; the length
of the portion in the radula-sac is 0.3 mm.; the entire length of the radula is therefore 1 mm.,

a gigantic size indeed. The radula is of a purèly distichous character as is obvious trom fig. 159;
the radula-bands operate as a pair of scissors. Only the lateral pharyngêal walls carry the
radula-bands; the dorsal wall is beset with long cilia, the ventral wal! with shorter ones. The
structure of the radula-sac is strange here, it being everywhere else a simple evagination of
the ventral pharyngêal wall. Here on the contrary the case is complicated; the pharynx has a
large ventral offset, but the radula is nol directly formed in this; the distal wall is invaginated
and it is only on the outside of the invagination that the radula is formed. The radula-sac is
encircled U strong muscles, presenting a peculiar structure: at several parts they broaden and
become transparent, with a great number of fine fibres. Sometimes the fibres are not present
and in that case the muscles become wholly transparent; nuclei occur only sporadically (fig. 160).
Around the pharynx these muscles are likewise met with (fig. 152).

The intestine has no regular septa, but is provided with irregular folds. A secretion
consisting of large brownish-green granules is formed by the wall. Figs. 161 — 163 represent
the course and opening out of the rectum.

The cloaca is a spacious cavity, lined with cubical epithelium. A considerable number ot
odlls are found; about 20 gill-lamellae with strongly folded wall. In fig. 162 at f is a fold of the
cloaca-wall, more proximally continuous with the latter. In fig. 163 the cloaca is slightly cross-
shaped: it widens more proximally (fig. 104). 2 Strong muscular bundies connect the ventral
cloaca-wall with the thin circular muscular layer under the hypodermis (fig. 165). The cloaca-
opening is situated in a superficial furrow (fig. 163); here the cuticle is traversed by a great
number of thin, closely packed spicula, the shape of which cannot be learned from my sections.

1 do not srive a reconstruction ot the gfenerative organs with their efferent canals, as
the peculiar structure of the cloaca-ducts would interfere with the clearness of the illustration.

The cloaca-ducts are coloured yellow in my figures-, for the sake of clearness the part
running proximally is of a pale yellow, the part proceeding distally of a dark yellow. Both the
genital glands, stretching a long way proximally contain mature eggs and spermatozoa. The
cloaca-ducts pass out of the pericardium as narrow, strongly winding tubes, the right cloaca-duct
being for this reason touched in fig. 166 3 times. More proximally they widen considerably
and become sac-shaj:>ed (fig. 171). They do not carry any appendages; they themselves perform
the duty of vesiculae seminales; numerous spermatozoa are contained in them. The wall is built
up of cubical ciliated epithelium. In figs. 169 and 170 the part running proximally merges into
the part running distally. The latter behaves likewise; it takes a winding course and is dilatecl
at different points. They unite into the precloacal organ, which is large and extends far proxi-
mally i/>. o.). Here appendages are absent too. The structure of the portion of the cloaca-ducts
running distally is in no war peculiar: cylindrical epithelium alternating with very slender cells;
more proximally the glandular cells are finely granular with round nuclei at the base, whereas
more distally and in the precloacal organ the glandular cells strongly secrete and are entirely
filled with deeply staining large granules.

2 Small copulation spicula are present (figs. 165, 166 c. sp.). They are short (0.2 mm.),
but comparatively broad and attached to the ventral muscles of the body-wall by tolerably
strong muscles. Probably they are partly calcareous and consist partly ot a cuticular mass; it

is also possible that the spicula are hollow and merely consist of cuticular matter. A cubical
epithelial layer surrounds them. Somewhat proximally from the cloaca-opening they appear on
the outside; here next to the left spiculum a smaller one is observed (fig. 165).

The heart does not furnish any peculiarities. Fig. 162 represents 2 proximal offsets
of the pericardium, the median walls of which are invaginated. Both invaginations unite and
form the atrium (fig. IÖ3«), continuous with the ventricle, an invagination of the dorsal pericardial
wall more proximally (figs. 164, 165 e1). A dorsal and ventral blood-sinus are present. Around
the gills a great number of blood-corpuscles are found, but no distinct blood-sinuses. The blood
consists of a very finely granular liquid, staining pale red, in which the blood-corpuscles are found.

It is impossible to follow the course of the nerves in the anterior part of the body amid
the numerous muscular fibres and glandular cells. The ganglion posterius superius is distinct
(fig. 162), as well as the commissure between the ganglia posteriora inferiora; but the commis-
sures between the ganglion posterius superius and the ganglia posteriora inferiora are absent.

The thick cuticle and the spicula remind us of Proneomenia, but the absence of
papillae, the distichous radula, the structure of the salivary glands and the presence of gills
are important points of difference. We see at once that it is related to Proparamenia and
Paramenia, but from the former it directly differs on account of the distichous radula. The
following are the points of resemblance it presents to Paramenia : the distichous radula, the
gills, the absence of papillae in the integument, the presence of some papillae on the ventral
side (cf. Pruvot 4 fig. 61), and, though in a lesser degree, the structure of the cloaca-ducts.
It is however advisable to keep both forms separate. In structure as well as in size the radula
and radula-sac diverge from those of Paramenia. The salivary glands are also of a different
structure and situation. In Paramenia the nervous system in the distal body-part is different
and the cuticle much thinner. It cannot be denied however that there is a close relation
between both forms.

Dondersia.

11. Dondersia annulata nov. spec. (Plate V, figs. 172 — 179).

Stat. 47. Bay of Bima (N. Sumbawa). 55 M. Upon Gorgonid. 1 Specimen.

Length-index 48. Pale brown with 30 white non-closed rings. 3 dorso-terminal sense-
knots. 1 pair of vesicular appendages of the cloaca-ducts.
East-Indian Archipelago. 1 Specimen.

Fig. 172 represents the animal, 4 times enlarged. The length is 29 mm.; average
diameter 0.6 mm.; the length-index is therefore 48. The animal has contracted very irregularly,
the transverse sections being consequently of very different sizes. The colour is a pale yellowish-
brown with a greyish gloss, owing to the spicula. 30 white rings occur, placed at irregular
distances from each other, not closed, but open on the ventral side. The ventral groove is visible
as a very narrow slit. The posterior part has a projecting lip (/>), opening into the alimentary
canal on the ventral side (;;/).

SIBOGA-EXPEDITIE XLVII. 5

34

This form possesses a very thin cuticle and flat spicula. The latter are represented in
fig. 173. The spicula of the body-wall are extremely minute, flat and more or less heart-shaped
with a thick border, imbricated (A). Amongst these, though less numerous, spicula of shape
B occur; spatula-shaped with border, or curved needies bluntly terminating. Along the ventral
groove long spicula (' are met with, which may also be flat, being in that case provided
with a border. On the white rings no special spicula are observed. These shapes may be
compared with those of Stylomenia Salvatori (Pruvot 10 fig. 3) and Dondersia festiva
11 3 fig. 2). Papillae are entirely absent.

There are 3 extremely minute dorso-terminal sense-knots, looking like small elevations,
which may be retracted or protruded by fine muscular fibres (figs. 178, 179 ds.).

The "Flimmerhöhle" is small. In the proximal part the "vordere Bauchdrüse" occurs:
large transparent fibrillar glandular cells; the "hintere Bauchdrüse" which is much more developed
and also met with along the ventral groove, has small cells, staining bright transparent red
with carmine. The ventral groove, which runs as far as the cloaca, contains 1 large fold.

What has been observed with respect to Dinomenia Hubrechti and Rhopalomenia
aglaopheniae holds good for this animal, viz. the mouth-cavity and the opening of the pharynx
are separated from each other, a separation much more complete than in the before-mentioned
species. In fig. 172 at ;// is the opening of the mouth-cavity; the name of mouth-cavity is justified
on account of its carrying similar organs (cirrhi and "Mundleisten") as the mouth-cavity of the
other Neomeniidae. Fig. 174 shows a transverse section through the proximal part of the body,
the mouth-cavity is distinct; in the section fig. 175, which is a more distal one, the mouth-
cavity is still visible {m. c.) whereas the opening of the pharynx is also visible.

The pharynx is a straight tube with a strongly folded wall, encircled by a strong circular
muscular layer: numerous unicellular glands, which may form a compact mass, surround it
(fig. 176, p. o-.). There are 2 tubular salivary glands (s. g.) which take a winding course, and
only extend a little distance distally (0.3 mm.). They are short tubes which unite, open out
into the ventral part of the pharynx close before the radula, and are surrounded by unicellular
glands, the contents of which are dischanjed Jnto them. These elands cannot be distineuished
from those of the pharynx, as is also the case with Dondersia festiva (Hubrecht 3, figs. 10, 11).
In Dondersia festiva and Stylomenia these salivary glands are likewise met with.

The radula, which is exceedingly small, is found somewhat more distally and consists of
a few (4?) conical teeth, situated behind each other. Fig. 177 shows such a tooth, strongly
enlarged ; as they are placed in a slanting line, the part 6 may be considered as the pedicle
of the following tooth, a being loose. The radula-sac is also very small, whereas any special
muscles and cartilao-inous cells are absent. A similar radula is only met with in Stylomenia
Salvatori and Dondersia festiva, though the data of the latter are insufficiënt.

The part of the pharynx, next to the radula is not distinguished from the preceding
portion in any respect and must therefore also be called pharynx; an oesophagus is absent.
The pharynx unites with the proximal coecum and these form together the wide intestine, which
is provided with regular coeca (lig. 178).

< >n comparing the nervous system with that of Stylomenia we observe the following

35

o

difference: a "nerf buccal moven" and "externe" cannot be demonstrated. The cirrhi and
" Mundleisten" are directly innervated from the cerebral ganglion; the sublingual ganglia on
the contrary are clearly discernible (fig. 176). The commissures between the ganglion posterius
superius and the ganglia posteriora inferiora are distinct ; this is hoewever not the case
with the commissure between the ganglia posteriora inferiora, which is not visible in my
longitudinal sections.

The animal is mature. The cloaca-ducts are of a simple structure. The part, passing out
of the pericardium proceeds first proximally as a straight, narrow ciliated tube, to bend after-
wards and to run distally. The cloaca-ducts coalesce; the precloacal organ is large and opens
into the cloaca. The part of the cloaca-ducts, running proximally, carries an appendage : a little
stalked vesicle (fig. 178) which may be compared with the vesicula seminalis of Stylomenia.

Copulation-spicula and "organes en cordon" are absent.

The cloaca is a small cavity, which is continued far distally into the pointed extremity
of the body.

Regarcling the heart I cannot give any reliable data. From fig. 179 it is evident that
the heart is clivided into 2 parts (atrium and ventricler), but from the longitudinal sections
the exact structure cannot be made out.

I believe that I have sufficiënt grounds for placing this form under Dondersia. Simroth
gives the following peculiarities for the genus Dondersia: "Gestreckt wurmförmig, cylindrisch;
Kopfende kolbig verdicht. Kloakenöftnung ventral. Schwanzende darüber fingerförmig. Fussrinne
biegt in die Kloake ein. Fuss vorhanden. Spicula nadel- oder schaufelförmig. Kiemen fehlen.
Radula vorhanden. Yentrale und dorsale Speicheldrüsen. Langen-index 10".

With respect to this the following must be noticed. Dondersia festiva has not 4 but
2 salivary glands, the clorsal ones being absent. The latter are mentioned by Simroth because
Hubrecht makes mention of a gland, opening out into the pharynx and dividing into two
more proximally (3 fig. 9 k). On looking very closely at fig. 9 of Huisrecht we may observe
however that the said gland is nothing but the mouth-cavity with the cirrhi and "Mundleisten";
Hubrecht's sections, which were thoroughly examined by me, do not leave the slightest doubt
on this point. The glands k' are present but must be regarded as accumulations of unicellular
crlands, also met with around the mouth.cavitv elsewhere ; of salivarv edands there can be 110
question here. From this it follows that also in Dondersia festiva the mouth-opening and opening
of the pharynx are separated from each other (cf. Hubrecht's fig. 9 and my figure 175). But
the ventral salivary glands of Dondersia festiva are structured like those of Dondersia annulata
and take a similar course. The radula of Dondersia festiva is monoserial and consists of (4?)
conical teeth behind each other. The structure of the pharynx and intestine is for both torms
exactly alike. The structure of the cloaca-ducts may also be compared : the vesiculae seminales
of Dondersia annulata may be compared with the tubes / and /' of Dondersia festiva (3 fig. 3);
the stalked vesicles A of Dondersia festiva however are absent here. The byssus-gland of
Dondersia festiva is not present here, but in my opinion this gland should be differently inter-
preted, being simply a proximal offset of the cloaca. The spicula of both forms are very much
alike. The finger-shaped projection of Dondersia festiva is not found here, but an indication of

36

it is shown in fio\ 179, where we observe that the cloaca extends far more distally. In Dondersia
festiva dors. .-terminal sense-knots also occur, 2 of which I can positively demonstrate. I hope
to make close observations of Dondersia festiva afterwards, but I take it for„ certain that both
forms are closely related.

Dondersia differs from Stylomenia in the structure of the nervous system and radula,
and in the absence of the "organes en cordon", met with in Stylomenia. Yet there is, no doubt,
a close relation with Stylomenia (cf. spicula, vestibulum, salivary glands, radula, cloaca-ducts of
Stylomenia).

New diagnosis for Dondersia.

Dondersia Hubrecht.

Body long, length-index 10 — 48. 1 ventral fold. Spicula needie- or spatula-shaped, flat.
Cuticle very thin, no papillae. Dorso-terminal sense-knots present. 1 pair of short ventral salivary
glands, which unite before opening out into the pharynx. Radula small, monoserial (4? teeth).
Mouth-cavity and pharynx-opening separated from each other. No copulation-spicula.

festiva Hubrecht.

Length-index 10. Violet; the proximal part of the body thickened. 2 Dorso-terminal
sense-knots. 1 pair of tubular and 1 pair of vesicular appendages of the cloaca-ducts.
Naples.

annulaia nov. spec.

Length-index 48. Pale brown with 30 white non-closed rings. 3 dorso-terminal sense-
knots. 1 pair of vesicular appendages of the cloaca-ducts.
East-Indian Archipelago. 1 Specimen.

Chaetoderma.

12. Chaetoderma Lovéni nov. spec. (Plate VI, figs. 180 — 203).

Stat. 35. 8°o'.3 S., n6°59'E. 1310 M. In mud. 2 Specimens and a fragment.

Length 15 — 21 mm.; length-index of the two known specimens 20 and 34. Colour
vellow-brown. Proximal part considerably thickened, distal part narrow but ending in a little
knob. Extremely glittering owing to the flat and broad spicula. Radula with 1 large tooth,
2 sickle-shaped teeth, 1 slender oblong tooth and different smaller ones (?). 4 salivary glands.
Liver very large, extending as far as the proximal part of the body. 3 Pairs of gill-retractors
and 1 large protractor. From 8 to 1 2 gill-lamellae. Ganglion posterius superius situated in
the pericardium.

East-Indian Archipelago. 3 Specimens.

Figs. 1 80 and 1 8 1 represent the two specimens. The length of the first specimen is
16 mm.: the diameter of the proximal part is 1.2 mm. and of the distal part 0.4 mm.; the
length-index is therefore 20.

3 7

The lemnh of the second specimen is 21 mm.; the diameter proximally 1 mm., distally
0.25 mm.; the length-index 34.

From the figures the difference in shape is clearly visible ; the one specimen is short
and broad, the other long and thin. This depends of course on the state of contraction and
thus the length-index is only of comparative value.

The animals are considerably thicker at the proximal portion, a fact, due to the strohgly
developed liver (L), which is situated more proximally than in Chaetoderma nitidulum. The
genital gland however extends far less proximally. A strong incision before the liver indicates
the spot, where the retractors of the proximal end attach themselves to the body-wall. The
proximal end is round and the mouth somewhat V-shaped. The distal part ends in a little
knob. The colour is a pale yellow-brown, but the skin is transparent and permits the dark-
coloured liver to show through, the animal being tinted consequently a dark violet. The spicula
are distinctly visible and this accounts for the animal's extraordinary gloss. Nothing is perceptible
of a dorso-terminal sense-organ.

The spicula are flat and broad (fig. 183 A), imbricated, with broad bases and somewhat
tapered; they are finely striped, the stripes crossing each other and giving the spicula a peculiar
design. At the posterior end long thin spicula occur (fig. 182), whilst around the mouth-opening
very minute spicula are found, represented in fig. 183 B. Thus the spicula differ in shape from
those of the known species of Chaetoderma. The cuticle is traversed throughout by spicula; at
the posterior and anterior end the cuticle is thicker and there the spicula stand erect (fig. 184),
in the middle region the cuticle is thinner whilst the spicula lie flat (fig. 185). The hypodermis
has the thickness of 1 cellular layer, with large nuclei; the vesicular "Riesenzellen" (Wirén) are
everywhere perceptible (fig. 184 R). Close behind the mouth-opening the cuticle is very thin;
in one of the specimens spicula are entirely wanting there, the sections being at the same time
not round but broadened on the ventral side (fig. 190); this peculiarity which is not presented
by the other specimen, is most probably a consequence of contraction.

An extremely smal! dorso-terminal sense-knot is present at a spot, similar to that of
Chaetoderma nitidulum.

Likewise as in Chaetoderma nitidulum the 3 muscular layers of the body-wall can only
be indicated in the anterior part, whilst behind the head only the circular muscular layer is
found. The 4 muscular regions formed by the longitudinal muscles can only be demonstrated
in the posterior part of the body and are only slightly developed; for the rest the longitudinal
muscles form 1 continuous layer. The separate muscular bundies of the proximal portion differ
from those of Chaetoderma nitidulum. 2 Dorsal and some lateral retractors separate from the
longitudinal muscles of the body-wall. The 2 dorsal ones (///) divide each of them into 2
smaller bundies, which run proximally and ventrally to the right and left of the pharynx and
attach themselves to the ventral body-wall in the anterior portion of the body; the lateral ones
(///) take a similar course. Besides these there are ventral muscles (///') which originate in the ventral
wall and attach themselves to the ventral body-wall behind the mouth-opening (figs. 189, 190).

The gill-retractors are entirely different from those of Chaetoderma nitidulum (figs. 196 — 200).
First there is a very strong muscle, running parallel to the gills, the fibres of which take a

38

longitudinal course (g. m. ; il attaches itself to the distal body-wall and may be considered a
protractor. Moreover there is a strong dorsal retractor (d. /-. i, which divides more proximally
into two and attaches itsell to the dorsal body-wall. Then there are also 2 lateral retractors
(/. rd, attaching themselves to the lateral body-wall and 2 ventral ones, having the same
relation to the ventral wall [v. r.).

The following must be noticed as regards the alimentary canal. Around the mouth-
opening there is a broad cuticle ("Mundschild" Wirén) cf. figs. 186 — 188 c\ in one of the
specimens this is almost entirely round, in the other it is somewhat V-shaped. The mouth can
be retracted, the mouth-opening lying consequently in a cavity, as is the case with only one
ot' the specimens (fig. 1 8S <•?) and not with the other (fig. 187). Around the "Mundschild" a great
number oi spicula are implanted (fig. 183 B). The mouth-opening itself is slitlike and narrow.

The narrow pharynx has 4 small salivary glands, as in Chaetoderma nitidulum, but
1 cannot indicate any buccal glands. lts muscular layer is extremely thin. Fig. 1S9 represents
the place where the pharynx passes into the intestine ; the latter is provided with a small
proximal coecum, as is the case in most of the Xeomeniidae.

The radula deserves mention. Figs. 191 and 192 represent the radula of one specimen,
figs. 193 and 194 that of the other (cf. Kowalevskv 13, hg. 1, 24 — 27 and Wirén 6a Plate V,
fig. 15). The large radular tooth dt is present as well as the 2 large pieces d. The httle
chitinous teeth, directly obvious in the sections on account of their yellow colour, are clearly
separatecl from them. In both specimens there are 2 large sickle-shaped cuticular pieces a,
which support little curved teeth. Moreover in both specimens an oblong piece b is found.
'I hey also possess a number of fragments, the original situation of which we can no more tracé
T course. The resemblance the}- present to other forms of Chaetoderma will be discussed
afterwards.

The intestine and the rectum do not furnish any peculiarities. As regards the liver,
Chaetoderma Lovéni presents greater similarity to Chaetoderma nitidulum than to Chaetoderma
radulifera. The liver is very large and extends from a place close behind the head to a good
way tlistally (fig. 195 /). It is so strongly developed as to push away the intestine; the latter is
present only in the shape of a very narrow tube (/). "Körnerzellen" as well as "Keulenzellen"
(Wirén) can be demonstrated, but I am as vet not certain about their situation.

Of the nervous system I will only mention the cerebral ganglion and the ganglion
posterius superius. Fig. 203 represents the cerebral ganglion li.g. ; the nuclei are found at the
periphery, the fibrillae more in the centre. To this cerebral ganglion 6 smaller ganglia are
attached, 4 of which are lateral (j, _/, 5, 6) and 2 proximal (/, 2). The shape of the cerebral
ganglion corresponds to that of Chaetoderma nitidulum, whilst the 6 round ganglia are called
by Wirén the "lobi laterales and anteriores". For Chaetoderma Lovéni however the separation
between the latter and the cerebral o-aiis-hon is much more distinct.

Around the mouth-opening numerous buccal ganglia are met with (figs. 186 — 187).

\\ e must notice the situation of the ganglion posterius superius, which is found dorsally to
the rectum (fig. 199). It is a remarkable fact, that the two distal offsets of the pericardium unite and
enclose the ganglion posterius superius, which lies therefore in the pericardium (fig. 201 G. p. s.).

39

Afterwards I hope to give a more detailed account of this for a new species of Chaetoderma
(Chaetoderma canadense) where even the ganglion posterius superius is found in the heart itself.

The heart consists of i atrium, which has a doublé origin, on account of 2 invaginations
of the wall of the distal pericardial offsets, which unite (fig. 201a). This atrium is spacious and
provided with a tolerably thick wall. The ventricle on the contrary is an invagination of the
dorsal pericardial wall and in communication with the atrium. My sections do not permit of a
more accurate observation of the heart.

The gills, which are broad and short, contain 8 or 12 gill-lamellae only.

The animals are males and the genital glands are fully mature. The latter and the
cloaca-ducts do not offer any peculiarities.

Chaetoderma Lovéni cliffers in many respects from the species of Chaetoderma already
known. It is clearly distinct from Chaetoderma nitidulum on account of its raclula with the
numerous teeth, and it differs likewise from Chaetoderma radulifera, which possesses a much
more developed radula. The radula of Chaetoderma gutturosum is more closely related to that
of Chaetoderma Lovéni, though there is a difference between the two. Besides the shape of
the spicula shows that we have to deal with a different species here.

13. Chaetoderma Wiréni nov. spec. (Plate VI, figs. 204 — 210).
Stat. 241. 40 24.3 S., I2Q°49'.3E. 1570 M. 1 Specimen.

Leno-th 11 mm. Length-index of the only badly preserved specimen 11. Proximally
slio-htly broader than distally. Colour greenish-brown. Spicula larger than those of Chaetoderma
Lovéni and more lance-point-shaped. Radula with 1 large tooth, 2 chitinous side-pieces, 2
chitinous sickle-shaped teeth and some smaller ones(?). 4 salivary glands. Liver large as in
Chaetoderma nitidulum. About 20 gilblamellae.

East-Indian Archipelago. 1 Specimen.

The length is 11 mm.; the diameter proximally over 1 mm., distally 1 mm. The length-
index is 11. The proximal end is bluntly cut off and the animal glitters owing to the thin spicula.
At the distal end there are also a number of straight, long spicula. The colour is a greenish-
brown. The mouth-opening is round and the liver shows through distinctly. Of the internal structure
I can give only very unsatisfactory information; the anterior portion has been well-preserved, but
the case is different with the posterior part, the organs of which are hardly perceptible.

Fig. 204 represents the animal 4 times enlarged. The dorso-terminal sense-organ is
large and extends as in Chaetoderma productum as far as the cloaca-border.

In appearance Chaetoderma Wiréni differs greatly from Chaetoderma Lovéni. YVhen only
slightly enlarged the differently shaped spicula become directly obvious ; they are much larger
here. In fig. 205 A the spicula of the body-wall are 75 times enlarged and show the difference
from fig. 183, also 75 times enlarged. The shape of the spicula is more pointed here; they
are ribbed length-wise. Fig. 205 B represents a spiculum of the posterior end, C the spicula
around the mouth-opening, present in great numbers. The cuticle is thicker than that of

40

Chaetoderma Lovéni; on looking at fig. 208, which represents a part of it, 125 times enlarged;
the entire difference trom fig. 185 (215 1 is directly noticed.

Here also the longitudinal muscular bundies do not form 4 muscular regions but 1
thin continuous layer. The retractors m, tri and tri' (figs. 206, 207) are also present here, but
they are much more strongly developed than they are in the preceding species.

The structure of the organs of the proximal part corresponds in some degree with that
of Chaetoderma Lovéni. The pharynx bas strongly contracted, in consequence of which the
mouth-opening is retracted and lies in a cavity (cf. figs. 188 and 206). The salivary glands are
present but I cannot demonstrate any buccal glands. I must make mention of the fact that
here too the intestine carries a small proximal coecum.

The structure of the nervous system coincides with that of Chaetoderma Lovéni; the
sublingual commissure is clearly discernible and provided with some small nerve-knots (cf. Wirén,
6a pi. VII, fig. 1).

The radula is noteworthy (figs. 209 — 210). The large tooth dt is present, as well as
the side-pieces d, which here are visibly provided with a chitinous covering. The 2 sickle-
shaped pieces a are also easily discernible and consist merely of chïtine. The other pieces are
fragments, the original situation of which cannot be traced. The narrow oblong piece b present
in Chaetoderma Lovéni is wanting in Chaetoderma Wiréni, which has only curved teeth ;
therefore there is a difference between the two forms in the structure of the radula.

The liver is large and of a similar structure to that of Chaetoderma nitidulum. The
genital gland is mature and compactly filled with spermatozoa. Of the organs of the posterior
body-part hardly anything has been preserved.

The number of the gill-lamellae can be indicated with certainty and is about 20.

Chaetoderma Wiréni differs in the first place from the known species of Chaetoderma on
account of the spicula, the shape of which may be compared with that of Chaetoderma niti-
dulum, gutturosum and radulifera. Vet it has to be kept distinct from these three forms on
account of the structure of the radula.

III. ON THE RADULA OF CHAETODERMA.

(Plate VI, figs. 211 — 216).

Especially after what has recently been published by Kowalevsky (13) it may be desirable
to give a short account of what is known of the radula of Chaetoderma. The fact, that the
radula of Chaetoderma is composed of different teeth is not new, when we remember what
Hubrecht (3 pag. 5 note) has written about it. Three years ago already I examined different
species of Chaetoderma and as I always met with a radula, consisting of different teeth I tried
to indicate one for Chaetoderma nitidulum too. I isolated the radula of this form with Eau de
Javelle, and like Kowalevsky I found the 2 small teeth situated upon the large one. Though

4i

I have nothing to mention about Chaetoderma nitidulum. I will here write down my obser-
vations of the radula of the other forms, a fuller description of which I hope soon to publish ;
for comparison is facilitated when all the figures with relation to the radula of Chaetoderma
are within our reach.

Figs. 214 and 215 represent sections of a species of Chaetoderma of unknown origin. There
beino- many points of conformity I feel justified in classing this specimen among Chaetoderma
Lovéni. The radula corresponds with that of Chaetoderma Lovéni; the large tooth dt, broken
here, the side-pieces d, the sickle-shaped teeth a and more especially the narrow oblong piece
ó, broken here also.

Figs. 2 1 2 and 2 1 3 represent the radula of a species of Chaetoderma of unknown origin
(present of Rev. Norman) which for the rest does not differ much from Chaetoderma nitidulum.
The large tooth dt and the side-pieces d are present; it is distinctly visible that the small
chitinous radula consists of a heart-shaped centre, 2 large and 2 smaller curved teeth and some
small ones.

Fig. 2 1 1 represents the radula of a species of Chaetoderma from Port-Hood (Canada)
which I intend to call Chaetoderma canadense. After isolation with Eau de Javelle the large
radular tooth is found whilst the 2 very small teeth noticed for Chaetoderma nitidulum are also
present; the latter are oblong, somewhat spindle-shaped, slightly curved but not sickle-shaped.
In the isolating the small teeth have changed places, but probably their positions were
similar to those of the teeth of Chaetoderma nitidulum (cf. Kowalevsky 13, fig. 27). To render
a comparison between the two radulas possible, I also give that of Chaetoderma nitidulum,
after isolation with Eau de Javelle (fig. 216); here the little teeth have also changed places :
in "canadense" there is however more difference in size between the large tooth and the small
ones, than there is in "nitidulum".

For Chaetoderma we can therefore distinguish 3 types of a radula :
i° 1 large tooth upon which 2 smaller teeth are placed : Chaetoderma nitidulum, productum

and canadense.
20 1 large tooth upon which there is a row of teeth : Chaetoderma gutturosum, Lovéni, Wiréni

and the above mentioned species of Norman (and "militare"?).
30 Several rows of 5 teeth, one behind the other. No large tooth : Chaetoderma radulifera.

Now we will look, whether there is any relation between these 3 groups. In "radulifera"
there are rows which consist of 5 teeth, but what do we observe in group 2 ? For this let
us compare Kowalevsky's figures 24 and 26 with my figures 191 — 194. The large tooth dt
is present in both forms ; my side-teeth d may be compared with d and d' of "gutturosum";
in "Lovéni" there are however only 2 such pieces. On comparing the sickle-shaped pieces a
we notice an important difference; whilst in "gutturosum" the pieces a form a closed ring,
they are in "Lovéni" visibly provided each with a small chitinous tooth; in the sections these
yellow teeth are clearly distinct from the evidently cuticular sickles. Kowalevsky does not
mention anything about this, neither does he say whether the sickle-shaped pieces of "gutturosum"
consist of chitine or not. Upon d a chitinous tooth is likewise met with; "gutturosum" is however
without the rectangular piece b. We may speak here too of a row of 5 teeth ; 2 chitinous

SIBOGA-EXPEDITIE XI. VII.

42

teeth resting upon d, 2 upon the sickles a and a rectangular one b. This row of teeth does
not correspond neither with the first, nor with the second row of "gutturosum" (Kowalevsky
13, fig. 25, pag. 276—277).

Though there are some points of resemblance a comparison is extremely difficult on
account of my sections being seriously injured. From the structure of the large tooth dt, which
in both species is somewhat fork-shaped, it is evident, that there may be some relation.

The question also arises whether Kowalevsky is justified in calling the pieces d and
d teeth ; is it not possible that they may be compared just as well with the mandibulae of
"radulifera" as with the cuticular "Leisten" of "nitidulum" (mandibulae, Kowalevsky). The same
is the case with the large tooth dt-, it appears to me that we have good reason not to consider
it as belonging to the radula and to compare it with the side-pieces (mandibulae?) d and d '.

In account of the piece 6 (fig. 192) the radula of "Lovéni" approaches more closely that
of "radulifera" where a similar piece is found in the middle of the row of teeth (Kowalevsky 13,
fig. 9 pc). Fig. 191 shows that there may have been still another row of teeth; an oblong piece ó,
which may better be compared with the piece pc of "radulifera", is likewise present. It is evident
therefore that the radula of "Lovéni" may be compared with that of "radulifera" and "gutturosum".

The radula of "Wiréni" presents other peculiarities; here the large tooth dt is of the ordinary
structure, but the two pieces d are, no doubt, chitinous, that is, surrounded by a chitinous mantle.
The latter may be compared with the large tooth dt of "nitidulum" and "canadense" which also
consists of cuticular matter, surrounded by a thin chitinous layerv rendering the tooth very brittle
after isolation (cf. fig. 21 6). Of this radula the sickles a are moreover quite chitinous and differ
therefore from those of "Lovéni" and "radulifera" (?), which are cuticular, whilst the teeth they
carry are. chitinous. For the rest there is nothing more to be said of the radula of "Wiréni".

We may compare the radula of the species of Chaetoderma (present of Rev. Norman)
with that of "radulifera", but a closer resemblance exists between it and "Lovéni"; the middle
piece è is heart-shaped but the 2 sickles are wanting; the teeth e have been situated perhaps
upon the side-pieces d and the teeth a may be compared with those on the sickles of "Lovéni";
these are however mere suppositions.

The radula of "nitidulum", "procluctum" and "canadense" may have developed from a
radula like that of "Wiréni"; the little teeth have disappeared ; only the 2 chitinous sickles
remain, whilst the large tooth and the side-pieces are still present.

At any rate it is evident, that the radula of Chaetoderma is of great importance : any
contribution to its knowledge is heartily welcome. A division into a number of smaller genera
may be expected in the future; the liver also presents important differences. Chaetoderma
radulifera with its well-developed radula and extremely small liver is perhaps the most primitive form ;
the other forms have developed with a rudimentary radula and strongly developed liver ]). The
question to which species of the Neomeniidae Chaetoderma is related, must still remain unanswered.

1) When this article was passing through the press, I examined a new species of Chaetoderma, brought home by the Challenger-
Expedition, which I intend to call Chaetoderma Challengeri. This species a description of which I hope soon to publish, has a purely
distichous radula, consistirjg of many rows of teeth, one behind the other, and a well-developed radula-sac. The liver on the contrary
is hardly developed at all.

43

IV. CONCLUSION.

Recapitulating the contents of the preceding pages, we come to the conclusion that the
Siboga-Expedition has been able to secure 65 specimens of Solenogastres, belonging to 8 genera
(4 new genera) and to 12 species (all of them new), viz;

Proneomenia Weberi 11 specimens Depth 22 — 1633 M.

Proneomenia longa 2 specimens Depth 1158 M.

Dinomenia Hubrechti 2 specimens Depth 73 M. and pelagic

Dinomenia verrucosa 11 specimens Depth 32 — 112 M.

Proparamenia bivalens 2 specimens Depth 82 M.

Rhopalomenia indica 28 specimens Depth 18 — 560 M.

Rhopalomenia debilis 1 specimen Depth 75 — 94 M.

Hemimenia intermedia 2 specimens Depth 69 — 75 M.

Cyclomenia holosericea 1 specimen Depth 918 M.

Dondersia annulata 1 specimen Depth 55 M.

Chaetoderma Lovéni 3 specimens Depth 13 10 M.

Chaetoderma Wiréni 1 specimen Depth 1570 M.
The different depths do not present any peculiarities on corriparison with those of the
known species; the greatest depth of Proneomenia Weberi (1633 M.) however, exceeds that
of the species of Proneomenia already described. This depth has only been surpassed by that of
Chaetoderma nitidulum (1250 fathoms, Simroth 7, pag. 208). Pelseneer (12) mentions as the
greatest depth 3088 M. This is based on an error. At St. 202 a depth of 3088 M. was indeed
met with ; but in the fishing the trawl was made no use of; only the horizontal cylinder was
used, the specimen of Dinomenia Hubrechti, caught in this case, being consequently found
living free at the surface, and apparently leading a pelagic life, which has hitherto not been
noticed among Solenogastres.

In various respects our knowledge of the Solenogastres has been extended by the
Indian forms.

There is good reason for dividing the Neomeniidae into 2 groups :

A) Those with a thick cuticle, papillae, and long pointed spicula in many layers one above
the other.

B) Those with a thin cuticle. without papillae, with flat, imbricated spicula.

Both groups must remain distinctly separated, only Paramenia might be called intermediate,
though it is more closely related to group B than to group A. I ara of Pruvot's opinion in
considering the type of group B the most primitive one.

Taking the radula however as the principal point of comparison, we notice 3 groups :

C) Forms with polystichous radula.

D) Forms with distichous radula.

E) Forms without a radula. All these forms may be considered as having sprung from forms
with radulas and should be considered specialized forms.

44

All forms of group A correspond with those of group d witli the exception of Dondersia
and Macellomenia; />' and P correspond likewise.

The question arises now, whether there is any relation between both groups and whether
there may be transition-forms between the forms with a thick cuticle, pointed spicula, papillae
and a polystichous radula, and forms with a thin cnticle, flat imbricated spicula, a distichous
radula, and without papillae.

Such a transition-form has been describecl in the first place by Pruvot for Stylomenia
(10): the radula of this form may have originated from that of Ismenia, whilst the radula ot
Stylomenia may have given rise to a form like that of Amphimenia and Proneomenia vagans
Kow. & Mar. In that case the integument and the spicula of Amphimenia must have developed
from those of Stylomenia; a transition-form between the two is wanting.

Stvlomenia also presents points of affinity to other forms. In the first place to Dondersia,
of which the radula has i purely conical tooth, the distichous character of which can no longer
be recognised, whilst Dondersia is in its turn related to Myzomenia and Nematomenia.

Moreover there is some relation between Stylomenia and Hemimenia on account of the
thin cuticle, but more especially on account of the "organes en cordon". A third line of
development leads therefore in the direction of Hemimenia and Neomenia.

A nother group may have developed from Ismenia in the direction of Paramenia. The cuticle
of Paramenia is thicker than that of Stylomenia but the papillae are still absent ; the spicula are long
and thin but the radula is distichous. A close relation of Paramenia is Proparamenia ; the radula
of the latter form is however monoserial. A close observation of this radula will still reveal its origin
from a distichous radula (cf. fig. 88); when the teeth of a distichous radula approach each other
and broaden whilst the basal ends fuse into each other, a radula like" that of Proparamenia may
orisrinate. From the latter form radula-forms like those of Macellomenia and Proneomenia may
spring. Pruvot mentions that in forms with a distichous radula the salivary glands open out
separately, while in those with a polystichous radula the salivary glands unite before opening out
into the pharynx. This view correct at the time he wrote, is no longer of value. Forms with a
polystichous radula like Proparamenia, Proneomenia Weberi, Proneomenia longa and Proneomenia
thulensis have 2 salivary glands, which remain separated. Pruvot says (10, pag. 486): "on concoit
que si les orifices (des glandes salivaires) viennent a se rapprocher, il en sera de mème des deux
rangées de crochets comprises entre eux, et quand les orifices se seront fusionnés en un, seul les
odontoblastes produiront une bandelette unique". This holds good for forms like Proneomenia
vagans, Dondersia and others but it is impossible that e. g. in Proneomenia Weberi it should be
because of the salivary glands, merging clearly separated into the pharynx that the polystichous
radula has sprung from a distichous radula. The polystichous radula of these forms is far better
explained by supposing it to have sprung from the radula-forms of Proparamenia and Paramenia.
The presence of the 2 broad radular teeth, which in Proneomenia Weberi and longa are found
in the middle of the radula (cf. fig. 17, 28) reminds me of the tooth of Proparamenia and is
in favour of his view. krom this circumstance it follows that it would be better perhaps not
to class the 2 above mentioned forms with the other species of Proneomenia as 1 genus.
Especially as far as the radula of Proneomenia is concerned, our knowledge is still insufficiënt,

45

but it is not improbable however that in the future the genus Proneomenia will be divided into
smaller genera. As Proneomenia Weberi and longa show the principal characteristics of the
genus Proneomenia (polystichous radula, structure of the integument, 2 salivary glands, no
gills), a division of this genus should as yet not be recommended.

What has been noticed in Proneomenia, holds good for Rhopalomenia. Whilst in Rhopalo-
menia aglaopheniae and Kisigi the loss of the radula points towards their origin from speciejs of
Proneomenia, it is much more probable that Rhopalomenia indica and debilis are related to a
form like Dinomenia. The numerous receptacula seminis of Rhopalomenia indica point towards
some relation with Dinomenia verrucosa, just as the rudimentary radula-sac of Rhopalomenia debilis
points to a certain relation with Dinomenia, which has a distichous radula. However a relation
between Rhopalomenia indica and Proneomenia thulensis is also very well possible. The absence
of a radula in Pronomenia and Dinomenia may give rise to forms closely resembling each other
both of them with a thick cuticle, pointed spicula in many layers, 2 long salivary glands, no radula.

Proparamenia and Paramenia differ considerably in the structure of the integument. A
transition-form between the two is not known, but the possibility of such a form is proved by
Cyclomenia, which has a thick cuticle and needle-shaped spicula, but is without papillae. For
the rest Cyclomenia and Dinomenia are related to Paramenia, and show that the integument
may develop in the direction of Proneomenia, whilst the radula remains distichous.

As a consequence of these facts, the relation between the known Neomeniidae may be
established as follows :

Dinomenia

Cyclomenia-

Pararrhopalia

Pruvotia

Strophomenia

Notomenia(?)

Rhopalomenia indica
and debilis

Proneomenia thulensis

Rhopalomenia aglaopheniae and Eisigi

Proneomenia

Proneomenia Weberi Proneomenia vagans Kow. & M

and longa

Proparamenia

Macellomenia
Paramenia

Amphimenia

Stylomenia

Hemimenia-Neomenia

— Dondersia'

Myzomenia

Nematomenia

Echinomenia lsmenia Lepidomenia.

46

About the relation with Chaetoderma nothing- can as yet be determined, which might
be expected from all I have told of its radula. The relation with Myzomenia of which Thiele
makes mention, can no more be demonstrated lor Chaetoderma, on account of its very com-
plicated radula.

In the preceding pages I have tried to explain the different relations of the Neomeniidae ;
for phylogeny my scheme is of no value of course. Perfect certainty can be obtained only
after repeated and close investigations of the known forms and of new ones which will probably
be discovered. In this respect the rich collection, brought back by the Siboga-Expedition, may
be considered an important extension of our knowledge of the Solenogastres.

LITERATURE REFERRED TO ').

i. A. A. W. HüBRECHT. Proneomenia Sluiteri, gen. nov. and spec. nov. Nied. Arch. f. Zool. 1881,
Suppl. 1—75.

2. A. KOWALEVSKV and MARION. Contributions a 1'histoire des Solenogastres on Aplacophores. Ann. du

Mus. d'Hist. Nat. de Marseille. Zoölogie Tom. III, 1S87.

3. A. A. W. HÜBRECHT. Dondersia festiva, nov. gen. nov. spec. Donders-feestbundel. 1888.

4. G. PRUVOT. Sur 1'organisation de quelques Néomeniens des cótes de France. Arch. de Zool. Exp.

Serie II, Tomé IX, 1891.

5. G. HEUSCHER. Zur Anatomie und Histologie der Proneomenia Sluiteri. Jen. Zeitschr. für Naturw.

Bd. XXVII, X. F. XX, 1892.
6a. A. WlRÉN. Studiën uber die Solenogastres. I Kongl. Svenska Vet. Ak. Handl., Band XXIV, n°. 12, 1891.
6b. II Bd. XXV, nn. 6, 1892.

7. H. SlMROTH. Alollusca in Bronn's Klassen und Ordnungen des Thierreichs. Leipzig, 1893.

8. J. THIEI.E. Beitrage zur vergl. Anatomie der Amphineura. Z. f. wiss. Zool. Bd. LVIII, 1894.
9. Zwei Australische Solenogastren. Zool. Anz. Bd. XX, 1897.

10. G. PRUVOT. Sur deux Néomeniens nouveaux de la Mediterranée. Arch. de Zool. Exp. Serie III,

Tomé VII, 1899.

11. J. Thiele. Proneomenia thulensis in Fauna arctica Romer und Schaudinn. Bd. I, 1900.

12. P. Pelsexeek. Les Néomeniens de 1'Expédition antarctique beige et la distribution géographique des

Aplacophora. Buil. de 1'Acad. roy. de Belgique, n". 9 — 10, pag. 528 — 534, 1901.

13. A. KoWALEVSKY. Sur Ie genre Chaetoderma. Arch. de Zool. Exp. et Gen. 3me Serie, Tomé IX, 1901.

1) For completeness' sake I may here yet mention the other publications concerning Solenogastres, which I have had no
occasion to refer to in the text.

S. I OVl .. Chaetoderma, ett nytt masksliigte. Oefvers. K. Vet. Ak. Förhandlgr. Stockholm 1844.

T. TüLLBERG. Neomenia, a new genus of Invertebrate Animals. Bih. till. K. Svensk. Vet. Akad. Handl. Bd. III, n° 13, 1875.

I GRAFF. Anatomie des Chaetoderma nitidulum Lov. Zeitschr. f. wiss. Zool. Bd. XXVI, 1876.

Xeomcnia, Proneomenia und Chaetoderma. Zeitschr. f. wiss. Zool. Bd. XXVIII, 1 S 7 7.

< ,. Vrmauer Hansen. Anatomisk Beskrivelse af Chaetoderma nitidulum. Xyt. Mag. f. Xaturvid. Bd. XXII, 1877.

I.i i ■; and DaNIELSSEN. Descriptions of new species belonging to the genus Solenopus, with some observations on their organisation.

Ann. Mag. Xat. Hist. 5 Serie III, 1S79.
A. Kowalevsky et A. F. Marion. Etudes sur les Neomenia. Zool. Anz. Bd. V, 1882.

F. SELENKA. Gephyrea. Challenger-Report. Zoology XIII, 1SS5.

1. \i;mai],k HaNSEN. Neomenia, Proneomenia und Chaetoderma. Bergens Museums Aarsberetning. 1888.

G. PRUVOT. Sur Ie développement d'un Solénogastre. Compt. rend. CXI, 1890.

CORRIGENDA.

Page
Page
Page
Page
Page
Page
Page
Page
Page
Page

4
5
6
6
6
9
9
1 1

■5 1

ne 3. for cuticula read cuticle.

ne 36 for discernable read disceinible.

ne 12 for cuticula read cuticle.

ne 1. for Neomenidae read Neomeniidae.

ne 8. for cuticula read cuticle.

ne 12, 15. for continuous in read continuous with.

ne 2S. for sinus read sinuses.

ne 39. for cuticula read cuticle.

ne 34. for cuticula read cuticle.

ne 6, 8. for cuticula read cuticle.

PLATES.

. X l.\ II. 1 1. F. \ istres

^ps*^

ts ,%Jïï

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Chromolith. P VV M. ' I

Figs.

I, 2.

Fig.

3-

Figs.

4 — io.

Fig.

1 1.

Fig.

12.

PLATE I.

Nervous system blue. Alimentary canal green. Heart and blood-sinuses red.

Cloaca-ducts yellovv. Appendages of the cloaca-ducts brown.

Integument, cloaca-wall, copulation-spicula, blood-gland, pericardium and muscles black.

Fig. i — 22. Proneomenia Weberi.

Proneomenia Weberi, 4 • ', drawn from spirit-specimens.

Spicula 125 . A of the body-vvall, B cloaca-spicula, C spicula from the hinder body-region,

D along the ventral groove.
Schematic sections along the lines AB — NO of fig. 11. 28 v. See text.
Reconstruction out of transverse sections of genital glands, pericardium, cloaca-ducts, part

of the cloaca and digestive canal. Dorsal view. c copulation-spiculum. 28
Epithelium of the wall of the cloaCa-pouch /; (cf. fig. 5), a cavity in which a cloaca-
spiculum. 215 X-
Fip-. 13. Reconstruction of the anterior part out of longitudinal sections. p wall of the pharynx,

a part of the mouth-cavity, enclosed by the "Mundleisten", in which the cirrhi are
found, b muscles of the pharyngeal fold. 28 X-
Figs. 14 — 16. Schematic transverse sections of the anterior part, cf. the lines AB — E F of fig. 13.

S septum, cc cartilaginous cells of the radula. 28 ■ .
Fig. 17 A. A longitudinal section through the radula. a radula-sac, b epithelial pouch. See text. 37 X.

B. A transverse section; the greater part of the teeth are broken. 2i7 X.

C. Row of teeth of the radula, isolated with Eau de Javelle. 88 X.
Fig. 18 A. Transverse section through a cloaca-duct.

B. Transverse section through the vesiculae seminales. 190 X.
Fig. 19. Transverse section through a copulation-spiculum with its muscular bundies. 125 X-

Fig. 20. Longitudinal section through the base of a copulation-spiculum (see text). 150 X.

Fig. 21 A. Idem. ƒ> protractors, r retractors. 28 X.

B. Point and middle piece of a copulation-spiculum, isolated with Eau de Javelle. 125 X-
Fig. 22. 5 Transverse sections through the pericardium with the heart.

A a the two distal pericardial invaginations, forming together :

Ba the atrium.

Cv the ventricle.

D av the right atrio-ventricular opening, with little sphincter. 56 X.

Figs. 23 — 40. Proneomenia longa.

Fig. 23. Proneomenia longa, 4 • , drawn from the spirit-specimen.

Fig. 24. Transverse section through the mouth-opening, along line A B of fig. 27. 24 X.

Fig. 25. Papillae of the integument. 315 X-

Fig. 26 A. Transverse section through the radula,

B. A hooked tooth. 190 X.
Fig. 27. See plate II. Reconstruction of the anterior part, out of transverse sections. a part of

the mouth-cavity filled with cirrhi ; b epithelial pouch of the radula. 24 X.
Transverse section through the radula in pouch /; (cf. fig. 17 A). 190 X-
Transverse section somewhat more distally; the teeth have disappeared; cuticular matter

is forméd. 190 X.
Schematic transverse sections through the postenor extremity. 28 y. ag preanal gland,

c s copulation-spiculum.
Transverse section through the heart. p pericardium, a atrium, bilobed, k invagination of
the dorsal pericardial wall, forming the ventricle more proximally, av left atrio-ventricular
opening with sphincter. 88 X-
Transverse section through the radula-sac. 215 X.
Epithelium of the dorsal cloaca-wall. 388 X-
Epithelium of the lateral cloaca-wall. 215 X.

Transverse section through the posterior end of the second specimen, cf. fig. 33. es small
copulation-spicula. 25 X.

Fig.

28.

Fig.

29.

Figs.

30—35-

Fig.

36.

Fig.

37-

Fig.

38.

Fig.

39-

Fig.

40.

. XI.VII. ||. I. Nu RSTR ' igast reS

lanan; 60 1

molith. 1'. W. M. Trap Leiden.

PLATE IL

Colours : see Plate I.

Fig. 27 : see Plate I.

Figs. 41 — 56. Dinomenia Hubrechti.

Fig. 41. Dinomenia Hubrechti, 4 > , from a spirit-specimen.

Fig. 42. Spicula, 316 x. A of the body-wall, B along the ventral groove.

Fig. 43. Reconstruction of the anterior extremity out of transverse sections. 39 X. a mouth-cavity,

(cirrhi not indicated) b cavity in which the pharynx opens out; e dorsal and proximal coecum.
Figs. 44 — 47. Schematic transverse sections along the lines AB — G H ol fig. 43. c muscle separating cavity

a and cavity b, cc cartilaginous cells. 39 X.
Fig. 48. Transverse section through the radula. 148 > . In muscle, sg salivary gland.

Fig. 49. Radula-teeth and fragments. 430 X-

Fig. 50. Transverse section through the radula-sac. 215 • . A more proximally, B more distally.

Fig. 51. Reconstruction of the posterior extremity, out of transverse sections, dorsal view. a vesicula

seminalis, /' receptaculum seminis, es copulation-spiculum. 23 X.
Figs. 52 — 55. Schematic transverse sections along the lines AB — G H of fig. 51. 23 • . es copulation-spicula.
Fig. 56. 6 Transverse sections through the pericardium and the heart. 75 X- a and b invaginations

of the distal and dorsal pericardial wall, forming together the atrium b 4- a. c invaginations

of the dorsal pericardial wall which form the ventricle, d see text.

Figs. 57 — 59. Proneomenia sp.

Fig. 57. Reconstruction of the posterior end out of transverse sections. Dorsal view. a proximal offset

of the cloaca, b coecum of the cloaca-ducts, e copulation-spiculum. 40
Figs. 58 — 59. Schematic transverse sections along the lines AB — CD of fig. 57. es copulation-spiculum. 37 X-

Figs. 60 — 75. Dinomenia verrucosa.

Fig. 60. Dinomenia verrucosa, drawn from life by Mr. HUYSMANS. Natural size.

Fig. 61. A young specimen, 4 X, drawn from a spirit-specimen.

Fig. 62. Spicula, 125 X. A of the body-wall, B and C along the ventral groove, D around the cloaca-

opening.

Fig. 63. Reconstruction of the anterior part of the specimen of fig. 60 out of transverse sections. 4 X.

a part of the mouth-cavity filled with cirrhi, b little dorsal coecum, c fold of the dorsal
wall of the mouth-cavity, d ventral coecum, r radula-sac, e tubular ventral appendage of
the pharynx, s g salivary gland, g g genital gland, m m pharyngeal muscles.

Fig. 64. Transverse section through the appendage e and the salivary gland s g. 88 X.

Figs. 65 — 6j. Radula-teeth and fragments. 88 X.

Fig. 68. Transverse section through the radula and radula-sac, b basal-membrane, / tooth. c pedicle. 39 X.

Fig. 69. Transverse section through the radula at the point where it bends into the radula-sac. 50 X-

Fig. 70. As fig. 63, anterior part of a young specimen. 12 •'. o opening of the ventral pharyngeal

appendage.

Figs. 71 — yj. Schematic transverse sections through the anterior part, along the lines AB — NO of fig. 63.
4 •. rs radula-sac, r radula.

. XI. VII. II. F. Nikrstrasz Solcnogastres.

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Figs.

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86.

Fig.

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Fig.

88.

PLATE III.

Colours : see Plate I.
Figs. jó — 82. Dinomenia verrucosa.

Figs. 76, TJ. see Plate II.

Fio-. 78. Reconstruction of the posterior extremity of a young specimen. 18 x- Dorsal view.

Figs. 79 — 82. Schematic transverse sections through the posterior extremity of another specimen, along
the lines A B — GH of fig. 78. 4 x.
figs. Si, 82. a atrium, v ventricle.

Figs. 83 — 100. Proparamenia bivalens.

Proparamenia bivalens, 4 x, from a spirit-specimen.

Spicula 316 x- A of the body-wall, B along the ventral groove.

Schematic transverse section through the anterior extremity along the lines AB — CD of

fig. 87. 30 x. sg glandular part of the salivary glands, sd salivary ducts, m muscle.

Reconstruction of the anterior extremity out of transverse sections, 30 X. o opening of

the right salivary duet .ï d.
Radula-teeth, 215 X-
Fig. 89. Transverse section through pharynx and radula r, 88 X.

Fig. 90. Transverse section through the radula-sac, r radula, rt fragments of radula-teeth (?),

cc cartilaginous cells, ph pharyngeal wall, 88 x-
Fig. 91. Pharyngeal glands, 88 X.

Transverse section through a salivary gland, 88 X. e epithelium of the salivary duet sd,

m circular muscle, sg glandular part.
Reconstruction of the posterior extremity out of transverse sections, 30 X. rs recepta-

culum seminis.
Schematic transverse sections along the lines A B — L M of fig. 93. c cloaca, a atrium,

ds dorsal sinus, v ventricle, 30 x-
5 Sections through the pericardium and the heart. 40 x- gs gill-sinus, a atrium, v ventricle,

ds dorsal sinus.

Figs. 101 — 112. Rhopalomenia indica.

Figs. IOI — 103. Rhopalomenia indica, drawn from spirit-specimens. 4 x-

Fig. 104. Spicula 50 X. A of the body-wall, B around the cloaca-opening, C along the ventral groove.

Fio-. 105. Reconstruction of the posterior extremity out of longitudinal sections, dorsal view. 18 x-

Fig. 106. Section along the line EF of fig. 105. 7 x-

Figs. 107, 108. Sections along the lines CD — AB of fig. 105. 11 X. eg cloaca-groove.

Fig. 109. Reconstruction of the anterior extremity out of longitudinal sections. 18 x. sg salivary duet,

Figs. 110, in. Schematic transverse sections along the lines AB — CD of fig. 109. 18 x. sg sublingual

commissure.
Fig. 112. Transverse section through a salivary gland. 88 X. ge glandular cells, sd salivary duet.

Fig.

92.

Fig.

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Figs.

94—99

Fig.

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PLATE IV.

Colours: see Plate I.
Fig. 113. Dinomenia Hubrechti. Glandular tissue around the salivary glands. 40 x-

Figs. 114 — 117. Rhopalomenia debilis.

Fig. 114. Rhopalomenia debilis, drawn from the spirit-specimen. 4 X.

Figs. 115, 116. Schematic transverse sections through the anterior extremity; fig. 1 16 more proximally. 40 X.

a salivary duet, b rudimentary radula-sac, hb "hintere Bauchdrüse".
Fig. 117. Transverse section through the rudimentary radula-sac. 215 X.

Figs. 118 — 140. Hemimenia intermedia.

Violet the penis-gland, orange the carina-pouches.

Fig. 118. Hemimenia intermedia, drawn from a spirit-specimen. 4 X.

Fig. 119. The same specimen from the dorsal side. 4 X-

Fig. 120. Spicula 215 X. a, f flat spicula of the body-wall and the carina, b lance-point-shaped

spicula of the carina-pouches, c, d, e pointed spicula along the ventral groove of the

body-wall.
Fig. 121. Hypodermal cells and cuticle of the body-wall. 316 X.

Fig. 122. The same of the carina-pouches. 316 X.

Fig. 123. Longitudinal median section through the anterior extremity out of transverse sections.

18 X. See text.
Figs. 124 — 130. Transverse sections along the lines A B — NO of fig. 123 vb "vordere Bauchdrüse",

li b "hintereBauchdrüse", er cirrhi, 111 mouth-opening, ml "Mundleisten", e/cilia. 18 x-
Figs. 131 — 143. Transverse sections through the posterior extremity. 18 X.

ƒ (figs. 130 — 133) represents the course of the blood, o opening of the precloacal organ

p o into the cloaca, r s receptaculum seminis. See text.

\I.YII. II. F. Nu RSi rasz Solenogasl

/'.

Xicrstrasz del.

i linmioliUi.P. W. M. Tra]. Leiden.

PLATE V.

Colours: see Plate I and Plate IV.

Figs. 141 — 145. Hemimenia intermedia.

Figs. 141- — 143. See Plate IV.

Fig. 144. Transverse sections through the gland of the penis-spicula. A the vesicles g and h have

not yet united, B the two vesicles are united. 125 X-
Fig. 145. Transverse sections through a penis-spiculum with its epithelial sheath. 125 X.

A distal, C proximal part.

Figs. 146 — 171. Cyclomenia holosericea.

Fig. 146. The animal, dravvn from the spirit-specimen. 4 x-

Fig. 147. Spicula. A of the body-wall, B along the ventral groove. 88 x-

Fig. 148. Section through the integument. 125 x.

Fig. 149. Transverse section through the ventral furrow, cf. fig. 164. 50 x-

Fig. 150. Reconstruction of the anterior extremity out of transverse sections. The red line indicates

the contour of the radula. 20 X- ƒ fold of the dorsal wall of the mouth-cavity.
Figs. 151 — 157 Schematic transverse sections along the lines AB — NO of fig. 150. 20 X.

f fold of the dorsal wall of the mouth-cavity, sg salivary gland, p, b and a see text,

r m radula-muscles. 20 X.
Fig. 158. Transverse section through the radula-sac. Radula-plates red. 88 x.

Fig. 159. Transverse section through the radula in the pharynx. 50 X.

Fig. 160. A part of the radula-muscles. 70 X.

Figs. 161 — 171. Schematic transverse sections through the posterior extremity. 20 X. See text.

a atrium, p o precloacal organ, / cloaca-fold, v ventricle, c. sp cloaca-spicula.

Figs. 172 — 179. Dondersia annulata.

Fig. 172. The animal, drawn from the spirit-specimen. 4 X.

Fig. 173. Spicula. 316 X. A and B of the body-wall, C along the ventral groove.

Figs. 174 — 176. Schematic transverse sections through the anterior extremity. 40 X. m c mouth-cavity,

rs radula-sac, p g pharyngeal glands, sg salivary glands.
Fig. 177. Transverse section through the radula. 50 X. a tooth, b base of the next tooth.

Figs. 178 — 179. Lateral and median longitudinal section through the posterior extremity. ds dorso-terminal

sense-knots.

■,/>/;,. XLVII. II. ]• . Nierstrasz Solcnogastres.

VT.

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PLATE VI.

Colours: see Plate I.

Figs. 180 — 203. Chaetoderma Lovéni.

Figs. 180, 181. Chaetoderma Lovéni, drawn from spirit-specimens. 4 X.

Fig. 182. Posterior extremity with the long straight spicula. 37 X.

Fio-. 183. Spicula 75 X. A of the body-wall, B around the mouth-opening, C oi the posterior extremity.

Fig. 184. Section through the integument. 125 X. R "Riesenzellen".

Fig. 185. Section through the integument of the middle region. 215 X.

Figs. 186 — 190. Schematic transverse sections through the anterior extremity. c "Mundschild", a see text,

m lateral, 111' dorsal, m" ventral retractors. 30 X.
Fio-s. 191 — 192. Sections through the radula of one of the specimens. 215 X. See text.
Figs. 193 — 194. Sections through the radula of the other specimen. 215 X. See text.
Fig. 195. Schematic transverse section through the middle region of the animal. 30 X. / liver,

i intestine.
Figs. 196 — 200. Schematic transverse sections through the posterior extremity. 39 X. g gills, g 111 gill-

protractor, vr ventral retractors, dr dorsal retractors, Ir lateral retractors, gps ganglion

posterius superius.
Fig. 201. Section through the pericardium, in which the ganglion posterius superius G.p.s. a atrium,

dr dorsal retractors. 75 X.
Figs. 202, 203. Sections through the cerebral ganglion hg, 3, ./, 3, 6 lateral ganglia, /, 2 proximal

ganglia. 50 X.

Figs. 204 — 210. Chaetoderma Wiréni.

Fig. 204. Chaetoderma Wiréni, drawn from the spirit-specimen. 4 X.

Fig. 205. Spicula. 75 A of the body-wall, B of the posterior extremity, C around the mouth-opening.

Figs. 206, 207. Schematic transverse sections through the anterior part 29 X. m' dorsal retractors, m lateral

retractors, m" ventral retractors.
Fig. 208. Section through the integument. 125 X.

Figs. 209, 210. Sections through the radula. 215 -X- See text.

Figs. 211 — 216.

Fig. 211. Radula of Chaetoderma canadense. 215 X. See text.

Figs. 212, 213. Radula of Chaetoderma sp. (NORMAN). 388 •'. See text. te tongue-cartilage, m muscle,

sg sublingual ganglion, E ciliated epithelium of the pharynx.
Figs. 214, 215. Radula of Chaetoderma sp. (= Chaetoderma Lovéni). 215 X. See text.
Fig. 216. Radula of Chaetoderma nitidulum. 215 X. See text.

RÉSULTATS DES EXPLORATIONS
ZOOLOGJQUES, BOTANIQUES, OCÉANOGRAPHIQUES ET GEOLOGIQUES

ENTKEPRISES AUX
INDES NÉEKLANDAISE3 OKIENTALES en 1899 1900,

a bord du SIBOGA

SOUS LE COM1TANDEMENT DE

G. F. TYDEMAN

PUBLIÉS PAR

MAX "VV E B E R.

Chef Je 1'expéditiuii.

*I. Introduction et description de 1'exnédition, Max \\ eter.
*I1. Le bateau et son équipement scieutilique, G. P. Tydeman,

III. Résultats hvdrographiques, G. F. Tydeman.

IV. Foraminrfera.
V. Radiolaria.

VI. Porifera, G. C. J. Vosraaei' et J. H. Vernhout.
VII. Hydropolypi, Ch. Julin.
VIII. Hydrocorallinae, S. J. Hickson.
IX. Siphonophora, Miles Lens et van Riemsdijk.
X. Hydromedusae, O. Maas.
XI. Scyphomedusae, O Maas.
XII. Ctenophora, MUe F. Moser.

XIII. Gorgonidae, Alcyonidae, J. Versluys.

XIV. Pennatulidae, S. J. Hickson.
XV. Actiniaria, P. Mc Murrich.

XVI. Madreporaria, A. Alcock et L. Döderlein.
XVII. Antipatharia, P. N. van Kampen.
XVIII. Turbellaria, L. von Graff et R. R. von Stommer.
XIX. Cestodes, J. W. Spengel.
XX. Nematodes, A. A. W, Hub recht.
XXI. Chaetognatha, G. H. Fowler.
XXII. Nemertini, A. A. W. Hub recht.
XXIII. Myzostomidae, R. R. von Stuiumer.
XXI Va. Polychaeta errantia, R. Horst.

XXIV*. Polychaeta sedeutaria, M. Caullery et F. Mes uil.
XXV. Gephyrea, C. Ph. Sluiter.
XXVI. Euteropueusta, J. W. Spengel.
XXVII. Brachiopoda, J. F. van liemmclen.
XXVIII. Bryozoa, S. F. H arm er.
XXIX. Copepoda, A. Scott.
XXX. Ostracoda, G. W. Muller.
XXXI. Cinhipedia, P. P. C. Hoek.
XXXIIa. Isopoda, H. J. Hansen.
XXXIIi. Epiearidae, J. Bon nier.

XXXIII. Amphipoda, J. Bonnier.

XXXIV. Caprellidae, P. Mayer.
XXXV. Stomatopoda, H. J. Hansen.

XXXVI. Leptostraca, H. J. Hansen.
XXXVII. Schizopoda, H. J. Hansen.
XXXVI II. Sersrestidae, H. .1. Hansen.
X.XXIX. Decapoda, J. G. de Man.
XL. Pantopoda, J. C. C. Loman.
XLI. Halobatidae, J. Th. O n d e m a n s.
XLII. Crinoidea, L. Döderlein p p.
XLIII. Echinoidea, J. C. H. de Meyere.
«XLIV. Holotburioidea, C. Ph. Sluiter.
XLV. Ophiuroidea, R. Kohier.
XLVI. Asteroidea, L. Döderlein.
«XLVH. .Solenogastres, H. F. Nierstrasz.
XLVIII Chitonidae, H. F. Nierstrasz.
XLIX. Prosobrauchia, M. M. Schepman.
L. Opisthobranchia, R. Bergh.
LI. Heteropoda, J. J. Tesch.
Lil. Pteropoda, J. J. Tesch.
LUI. Lamellibranchiata. P. Pelseneer et Ph. Dautzenberg.
LIV. Scaphopoda.
LV. Cephalopoda, L. Joubiu.
LVI. Tuuicata, G. Ph. Sluiter.
LVII. Pisccs, Max Weber.
LVIII. Cetacea, Max Weber.
LIX. Liste des algues, M»'e A. Weber.
*LX. Halimeda, MUe E. S. Barton.
LXI. Melobesieae, M'"° A. Weber et M. Foslie.
LXII. Diiioflagellata. Coccosphaeridae, J. P. I.otsy.
LX1II.J Diatomaceae, J. P. Lotsy.
LX1V. Deposita marina, O. B. Böggild.
LXV. Résultats géologiques, A. Wichmann.

Siboga-Expeditie

THE

SOLENOGASTRES OF THE SIBOGA-EXPEDITION

BY

H. F. NIERSTRASZ

>ï

Utrecht.
With six plates

Monographie XLVII of:

C /

UITKOMSTEN OP ZOOLOGISCH,
BOTANISCH, OCEANOGRAPHISCH EN GEOLOGISCH GEBIED

verzameld in Neder landsch Oost-I ndië 1899 — 1900

aan boord H. M. Siboga onder commando van
Luitenant ter zee ie kl. G. F TYDEMAN

UITGEGEVEN DOOR

Dr. MAX WEBER

Prof. in Amsterdam, Leider der Expeditie

(met medewerking van de Maatschappij ter bevordering van het Natuurkundig
onderzoek der Néderlandsche Koloniën)

>s^x

BOEKHANDEL EN DRUKKERIJ
E. J. BRILL

LEIDEN

h .^,^0^^^,

' 1 , _ 'm i:.i .ui __

Publié Juin 1902

* Les numéros avcc un astérique ont déja para.

Voor de uitgave van de resultaten der Siboga-Expeditie hebben
bijdragen beschikbaar gesteld:

De Maatschappij ter bevordering van het Natuurkundig Onderzoek der Nederlandschc
Koloniën.

Het Ministerie van Koloniën.

Het Ministerie van Binnenlandsche Zaken.

Het Koninklijk Zoologisch Genootschap » Natura Artis Magistra" te Amsterdam.

De >Oostersche Handel en Reederij" te Amsterdam.

De Heer B. H. de Waal, Consul- Generaal der Nederlanden te Kaapstad.

CONDITIONS GÉNÉRALES DE VENTE.

i°. L'ouvrage du „Siboga" se composcra d'une série de monographics.

2°. Ces monographies paraitront au fur et a mesure qu'elles seront prêtcs.

3°. Le prix de chaque monographie sera différent, mais nous avons adopté comme base générale du prix de
vente: pour une feuille d'impression sans fig. flor. 0.15; pour une feuillc avec fig. flor. 0.20 a 0.25 ;
pour une planchc noire flor. 0.25 ; pour une planche coloriée flor. 0.40.

40 _U y aura deux modes de souscription :
■ a. La souscription a l'ouvrage complet.

ff. La souscription a des monographies séparées en nombre restreint.
Dans ce dernier cas, le prix des monographies sera majoré de 25 %•

50. L'ouvrage sera réuni en volumes avec titres et index. Les souscripteurs a l'ouvrage complet recevront
ces titres et index, au fur et a mesure que chaque volume sera complet.

Déja paru:

le Livraison. (Monographie XLIV) c. Ph. Sluiter, Die Holothurien der Siboga-
Expedition. Mit 10 Taf. / 7.50

Pour les souscripteurs a touwage compht. „ O. —

2«' Livraison. (Monographie LX) e. s. Barton, The genus Halimeda. With
4 plates /2.40

Pour les souscriptewrs a Vouvrage complet. „ 1.80

3°. Livraison. (Monographie I) »lax Weber, Introduction et description de
1'expediiion. Avec Liste des Stations et 2 Cartes , . f 9. —

Pour les souscripteurs a Vouvrage complet. „ D.75

4° Livraison. (Monographie II) G. f. Tydeman. Description of the ship and

appfiancés usèd for scientific exploration. With 3 plates and illnstrations.

/2.50

Pour les souscripteurs h Touwage rum plet. „ 6. —

/

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